Iran has said it will no longer abide by any limits of an international nuclear deal after the US assassination of top general Qassem Soleimani.

In a statement broadcast on state TV, the government said it would no longer respect restrictions on enrichment of uranium, or research and development, representing another major blow to any hopes of restoring relations between Washington and Tehran on a day that saw hundreds of thousands take to the streets of cities and towns across Iran to mourn Soleimani and demand retaliation.

The announcement marks the most serious blow yet to the 2015 accord, agreed between Iran and a group of world powers known as the P5+1 - the US, UK, France, China, Russia and Germany - that aimed to prevent Tehran from building an atomic weapon by imposing restrictions on its sensitive nuclear activities and allowing inspections by international experts in return for the lifting of economic sanctions.

US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Show all 35 1 /35 US airstrike kills Iran's Qassem Soleimani: Fallout in pictures US airstrike kills Iran's Qassem Soleimani: Fallout in pictures This photo released by the Iraqi Prime Minister Press Office shows a burning vehicle at the Baghdad International Airport following an airstrike in Baghdad, Iraq, early Friday 3 January AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures The wreckage of the car in which general Soleimani was travelling when a targeted US airstrike struck outside Baghdad International Airport on 3 January Ahmad Al Mukhtar via Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Demonstrators burn the US and British flags during a protest in Tehran after general Soleimani was killed in a targeted airstrike by American forces Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A burning vehicle at the Baghdad International Airport following an airstrike. The Pentagon said Thursday that the US military has killed general Qassem Soleimani, the head of Iran's elite Quds Force, at the direction of Donald Trump AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Protesters burn Israeli and US flags as thousands of Iranians take to the streets to mourn the death of general Soleimani at the hands of America EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Supporters of Donald Trump pray at an 'Evangelicals for Trump' campaign event held on the day following the killing of general Soleimani. At the event, the president praised the "flawless strike that eliminated the terrorist ringleader" AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A huge procession of mourners gather in Baghdad for the funeral of general Soleimani on 4 January AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Thousands of Iranians take to the streets to mourn the death of Soleimani during an anti-US demonstration to condemn the killing of Soleimani, after Friday prayers in Tehran, Iran EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iraqis perform a mourning prayer for slain major general Qasem Soleimani of the Iranian Revolutionary Guards at the Great Mosque of Kufa AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A billboard reading 'Death to America and Israel', installed by Iran-backed shiite armed groups at a street in Jadriyah district in Baghdad, Iraq EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A handout picture provided by the office of Iran's supreme leader Ayatollah Ali Khamenei shows him visiting the family of Soleiman KHAMENEI.IR/AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Thousands of Iranians take to the streets in Tehran EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Pakistani Shiite Muslims burn a mock of a US flag as they hold pictures of General Qasem Soleimani during a protest against the USA, outside the US Consulate in Lahore, Pakistan EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iran's Ambassador to Lebanon Mohammed Jalal Feiruznia, looks to a portrait of Soleimani, as he receives condolences at the Iranian embassy, in Beirut, Lebanon AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures People make their way on the street while a screen on the wall of a cinema shows a portrait Soleimani in Tehran AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Aziz Asmar, one of two Syrian painters who completed a mural following the killing of Iranian Revolutionary Guards commander Qasem Soleimani poses next to his creation in the rebel-held Syrian town of Dana in the northwestern province of Idlib AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A demonstration in Tehran AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures An anti-US demonstration to condemn the killing of Soleimani, after Friday prayers in Tehran EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Mujtaba al-Husseini, the representative of Iran's supreme leader Ayatollah Ali Khamenei, delivers a speech in the holy shrine city of Najaf AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Pakistani Shiite Muslims burn a mock of a US and Israeli flags as they hold pictures of General Qasem Soleimani during a protest against the USA, outside the US Consulate in Lahore, Pakistan EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Protesters demonstrate in Tehran AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Pakistani Shi'ite Muslims hold pictures of General Qasem Soleimani during a protest against the USA, in Peshawar, Pakistan EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Protesters, holding a photograph of the leader of the People's Mujahedin of Iran Massoud Rajavi, outside Downing Street in London PA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Protesters burn a US flag in Tehran AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A Syrian man offers sweets to children to mark the killing AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranian worshippers attend a mourning prayer for Soleimani in Iran's capital Tehran AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Kashmiri Shiite Muslims shout anti American and anti Israel slogans during a protest AP US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranian worshipers chant slogans during Friday prayers Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures A protest against the USA, in Islamabad, Pakistan EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranians burn a US flag in Tehran EPA US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Supporters of the National Council of Resistance of Iran in Germany (NWRI) protest outside Iran's embassy in Berlin, Germany Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Supporters of the National Council of Resistance of Iran in Germany (NWRI) protest outside Iran's embassy in Berlin Reuters US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranian worshippers in Tehran AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Vehicles of the United Nations Interim Forces in Lebanon (UNIFIL) patrol a road in the southern Lebanese town of Kfar Kila near the border with Israel. Following morning's killing of Major General Qasem Soleimani, Lebanon's Iran-backed Hezbollah movement called for the missile strike by Israel's closest ally, to be avenged AFP via Getty US airstrike kills Iran's Qassem Soleimani: Fallout in pictures Iranian women take to the streets in Tehran EPA

It was considered a triumph by the Obama administration after years of tension over Iran's nuclear capabilities and intentions, but President Trump abandoned the deal in May 2018 in favour of a policy of 'maximum pressure' against Tehran, with crippling sanctions against its financial and oil sectors.

The other parties disagreed and tried to keep the deal in place, but the new US sanctions undermined the accord and its credibility was gradually eroded.

The announcement came hours after Iraq’s parliament voted to oust US and other foreign troops fighting Isis, delivering a blow to efforts to fight the jihadi group following Washington’s decision to assassinate Soleimani in an airstrike.

Iraq’s parliament convened and quickly passed the preliminary vote not only for the removal of foreign troops but also to submit a complaint to the United Nations against the US for violating the country’s sovereignty, marking a nadir in relations between Washington and Baghdad – where the airstrike took place in the early hours of Friday.

“Despite the domestic and international challenges that we may face, this choice remains the best for Iraq,” Iraq’s caretaker prime minister, Adel Abdul Mahdi, told lawmakers.

“Iraq lived without foreign forces in the period between 2011 and 2014 and its relationship with the US and any other party did not deteriorate.”

US forces in Iraq issued a statement saying they had “paused” anti-Isis efforts over the tensions with Iranian-backed forces a day after Nato nations declared they were pulling all troops out of the country.

A pullout of US and other international troops currently training and providing support to Iraqi forces could jeopardise efforts against Isis remnants attempting to stage a comeback. The group took over a third of the country during the three-year period when US troops were absent, sacking the number two city of Mosul after Iraqi forces crumbled.

The UK government urged Iraq to allow soldiers to remain in the country to continue the fight against Isis to stop any resurgence by the terror group.

Some 400 UK troops are stationed in Iraq to counter the threat from Isis, while the US has 5,200, prompting fears that a withdrawal could seriously harm the battle against the extremist group.

The Ministry of Defence was believed to be waiting for the decision of the Iraqi government before taking action over the soldiers, based there as part of a US-led coalition.

"We urge the Iraqi government to ensure the coalition is able to continue our vital work countering this shared threat," a MoD spokesperson said.

​The killings, ordered by Mr Trump in response to attacks on US sites in Iraq by Iranian-backed militias, have roiled the already volatile Middle East and upped preparations for a long-dreaded war as diplomats frantically sought to defuse the crisis.

Iraqis carry a mock coffin as they march in a symbolic funeral procession (AFP)

The bodies of Soleimani and Iraqi militia leader Abu Mahdi al-Mohandes were transported to the Iranian eastern shrine city of Mashhad on Sunday for burial.

Video footage showed thousands of emotional, grieving Iranians swarming around a white truck carrying their bodies through the centre of the city in scenes reminiscent of the death of Iran’s revolutionary founder, Ayatollah Ruhollah Khomeini, some three decades ago.

Mashhad is the city where a late 2017 uprising against the government that turned into a nationwide series of protests began. Soleimani, a pillar of the establishment, was celebrated even in anti-regime hotspots gripped only weeks ago by protests demanding political change.

Earlier video footage from a helicopter showed a lengthy procession of Iranians dressed in black gathering stretched along a long boulevard through the streets of central Ahvaz, capital of a largely ethnic Arab southwestern Iranian province that has been the scene of scores of anti-government protests since late 2017.

City officials renamed Ahvaz’s international airport after the “martyr” Soleimani.

The commander of Iran’s clandestine overseas service was regarded as a popular figure in Iran, credited by many for helping to defeat Isis and respected for publicly declining to use his celebrity to pursue political office.

It remains unclear whether his killing will quell the nascent movement against the regime that Washington hawks who have Mr Trump’s ear had been counting on to topple it.

But for now, few inside Iran were speaking of the economic troubles that had sparked an uprising in November that left scores of people dead, as Iranian officials and some segments of the public sought revenge, and officials spoke of war.

As Iran’s parliament opened, scores of Iranians lawmakers who gathered for an emergency session waved their fists in the air and chanted “Death to America”.

Shia Muslims march to protest against the US strike that killed Soleimani (AFP)

But Iranian leaders also went out of their way to insist they did not seek to harm American citizens.

Iranian leaders appear to have a sophisticated understanding of US domestic political issues, and state media has highlighted comments by Democratic Party officials criticising Trump’s Iran policies, including his decision to abruptly abandon the nuclear deal with Iran that had been forged by his predecessor.

“We have zero problems with the American people,” Hesameddin Ashena, an adviser to President Hassan Rouhani, wrote on Twitter. “We even achieved deals with previous US administrations. Our sole problem is Trump. In the event of war, it is he who will bear full responsibility.”

One hardline Iranian lawmaker, Abolfazl Aboutorabi, said that Iran “can attack the White House itself”, in retaliation for the killing. “We can respond to them on American soil,” he was quoted as saying.

But more senior Iranian officials sought to place limits on any response, even after Mr Trump threatened to destroy 52 Iranian targets including cultural sites important to Iranian people in a bizarre and angry tweet on Saturday.

Iranians gather in the northeastern city of Mashhad (AFP)

“The response will definitely be military and against military sites,” Hossein Dehghan, a military adviser to Iran’s supreme leader, Ali Khamenei, told CNN. “It was America that started the war. Therefore they should expect appropriate reactions to their actions.”

In a speech from Lebanon broadcast on television, Hezbollah leader Hassan Nasrallah, a staunch ally of Iran and close friend of Soleimani, threatened US troops but cautioned against any attacks that would harm American civilians.

“When the coffins of American soldiers and officers begin to be transported ... to the United States, Trump and his administration will realise that they have really lost the region and will lose the elections,” he said, adding US civilians in the region “should not be touched” because this would serve Trump’s agenda.

Iranian hardline lawmaker Mojtaba Zonnour said: ​”If they target our cultural centres, we will hit their vessels and their bases.”

Diplomatic attempts to defuse the crisis continued. Oman, an Arabian peninsula nation with strong ties to both Iran and the US, urged the countries to turn to diplomacy.

State television shows emotional mourners in Iranian city of Mashhad swarming around a truck carrying the bodies of Qassem Soleimani and Abu Mahdi al-Mohandes

Russia and China, both permanent veto-wielding members of the United Nations Security Council, issued a statement condemning the US assassination and cautioning that “military adventurism is unacceptable”, according to the Xinhua news agency.