Tariq al-Hashemi charged with masterminding death squads against rivals, as at least 100 die in bombings and shootings

Iraq's fugitive Sunni vice-president was sentenced on Sunday to death by hanging on charges he masterminded death squads against rivals in a terror trial that has fuelled sectarian tensions in the country. Underscoring the instability, insurgents unleashed an onslaught of bombings and shootings across Iraq, killing at least 100 people in one of the deadliest days this year.

It appeared unlikely that the attacks in 13 cities were all timed to coincide with the afternoon verdict that capped a month-long case against Tariq al-Hashemi, a longtime foe of Shia prime minister Nouri al-Maliki. Still, taken together, the violence and verdict could energise Sunni insurgents bent on returning Iraq to the brink of civil war by targeting Shia and undermining the government.

Hashemi fled to Turkey in the months after the Shia-led government accused him of playing a role in 150 bombings, assassinations and other attacks from 2005 to 2011, years in which the country was mired in retaliatory sectarian violence that followed the 2003 US-led invasion that ousted Saddam Hussein's Sunni regime. Most of the attacks were allegedly carried out by Hashemi's bodyguards and other employees, and largely targeted government officials, security forces and Shia pilgrims.

The vice-president declined to immediately comment on the verdict after meeting with the Turkish foreign minister Ahmet Davutoglu in Ankara. He said he would "tackle this issue in a statement" in coming hours.

The politically charged case which was announced the day after US troops withdrew from the country last December sparked a government crisis and fuelled Sunni Muslim and Kurdish resentment against Maliki, who critics say is monopolising power.

Violence has ebbed significantly, but insurgents continue to stage high-profile bombings and shooting rampages. Al-Qaida's Iraq branch has promised a comeback in predominantly Sunni areas from which it was routed by the US and its local allies after sectarian fighting peaked in 2007.

"These attacks show al-Qaida's ability to hit any place in Iraq and at any time," said Ali Salem, 40, an elementary school teacher in Baghdad. "The lack of security could take us back to zero."

The worst violence on Sunday struck the capital, where bombs pounded a half-dozen neighbourhoods – Sunni and Shia – throughout the day.

The deadliest attacks in Baghdad hit Shia areas on Sunday evening, hours after the Hashemi verdict was announced. In all, 32 people were killed in the capital and 90 wounded, according to police and hospital officials.

The countrywide attacks began before dawn, with gunmen killing soldiers at an army post in the central Iraqi city of Dujail. A few hours later, a car exploded in a lot where police recruits were waiting to apply for jobs outside Kirkuk in the country's north. Dujail and Kirkuk are former insurgent strongholds.

During the day, at least 100 people were killed and more than 330 wounded in at least 21 separate bombings and shooting attacks, according to reports from police and hospital officials. No group immediately claimed responsibility, but Iraq's interior ministry blamed al-Qaida.

"The attacks today on the markets and mosques are aimed at provoking sectarian and political tensions," the ministry said in a statement. "Our war against terrorism is continuing, and we are ready."

The courtroom at Baghdad's criminal court was silent as the presiding judge read out the verdict. It convicted Hashemi and his son-in-law, Ahmed Qahtan, of organising the murders of a Shia security official and a lawyer who had refused to help the vice-president's allies in terror cases. The two defendants were acquitted in a third case of the killing of a security officer due to a lack of evidence.

The court sentenced both men in absentia to death by hanging. They have 30 days to appeal the verdict and could win a retrial if they return to Iraq to face the charges. Hashemi has been in office since 2006 and is on Interpol's most-wanted list, but Turkey has shown no interest in sending him back to Baghdad.

The defence team began its closing statement with a searing indictment of Iraq's justice system, accusing it of showing no independence and siding with the Shia-led government.

"From the beginning and through all procedures it has become obvious that the Iraqi judicial system has been under political pressure," attorney Muayad Obeid al-Ezzi, the head of the defence team, told the court.

The presiding judge immediately interjected, warning that the court would open legal proceedings against the defence team if it continued to heap accusations on the court or the legal system.

Reaction to the verdict was largely along sectarian lines on the streets of Baghdad.

Sunni lawyer Abdullah al-Azami called the trial "another farce to be added to the Iraqi judicial system".

Shia pharmacist Khalid Saied, meanwhile, said he supported the verdict and hoped the government would broadcast all the evidence against Hashemi "so that the entire world knows him".

Sunday's violence came amid fears that the insurgency has gained new strength after suffering heavy setbacks in US and Iraqi offensives. Four of the attacks targeted Kirkuk, where city police commander Sarhad Qadir blamed the violence on al-Qaida.

The carnage stretched into the country's south, where bombs exploded in the Shia-dominated city of Nasiriyah, 200 miles south-east of Baghdad. The blasts were near the French consulate and a local hotel in the city, although the consulate did not appear to be a target of the attack.

Local deputy health director Dr Adnan al-Musharifawi said two people were killed and three were wounded at the hotel, and one Iraqi policeman was wounded at the consulate. Musharifawi said no French diplomats were among the casualties. In Paris, France's foreign ministry said it "condemns with the greatest severity" the wave of attacks.

Smaller attacks on Sunday also struck nine other cities. It was one of the worst outbreaks of violence in Iraq in 2012, although the single deadliest day was 23 July, when least 115 people were killed – the most in more than two years.