US officials suspect that a Panamanian-flagged oil tanker that stopped transmitting its location after straying into Iranian waters may have been hijacked by Iran’s Revolutionary Guards.

Iran’s semi-official news agency ISNA said on Tuesday that the country’s navy came to the assistance of the Panamanian ship MT Riah after it had mechanical problems.

“An international oil tanker was in trouble due to a technical fault in the Persian Gulf. After receiving a request for assistance, Iranian forces approached it and used a tugboat to pull it towards Iranian waters for the necessary repairs to be carried out,” ISNA said.

US intelligence is concerned that the ship could have become a victim of Iranian manoeuvres intended to put pressure on Washington to lift crippling economic sanctions as it travelled through the strait of Hormuz, a vital route for oil shipping.

The tracking report of the Panamanian ship MT Riah from MarineTraffic.com showed the vessel began its journey near a port off the coast of Dubai, in the United Arab Emirates, on 5 July. It was then tracked near the coast of Ras al-Khaimah before changing course and travelling north towards Iranian waters, after which it stopped transmitting its signal on Sunday at about 4.30am local time (0100 BST).

Its last known location was in Iranian territorial waters near Qeshm Island, where the Revolutionary Guards have a base.

Ranjith Raja, an analyst at Refinitiv, a data firm, said the tanker had not switched off its tracking in three months of trips around the UAE. “That is a red flag,” he said.

The ship had been operating in the UAE between the cities of Sharjah and Fujairah over the past year and is owned by Prime Tankers, which operates out of Dubai.

The UAE has said it does not own or operate the ship and no distress signals were sent. The UAE said it was working with its international partners to discover the ship’s location.

Donald Trump did not comment on the tanker on Tuesday but claimed he was making a lot of progress with Iran and said he was not looking for regime change. He set conditions for talks including a withdrawal from Yemen. Iran denies it has any presence in the country.

The uncertainty over the ship’s whereabouts follows previous unattributed attacks on Gulf shipping as well as an attempt to intercept a British ship in the Gulf a fortnight ago.

Q&A Why is the Gulf of Oman so important for shipping oil? Show Hide The strait of Hormuz, which provides passage from the Gulf of Oman to the open sea, is the most important gateway for oil exports in the world. With Iran on its northern shore, and the UAE and Oman on its southern shore, the US Energy Information Administration (EIA) calls it the world’s worst 'chokepoint' In 2016, 18.5m barrels of crude oil were transported each day through the strait of Hormuz, compared with 16m through the strait of Malacca, which runs between the Indonesian island of Sumatra, Malaysia and Thailand, connecting the Indian Ocean with the South China Sea. 5m barrels of crude oil are transported annually through the next largest chokepoint, the Suez canal. Phillip Inman

It also followed the seizure of an Iranian oil tanker, Grace 1, off Gibraltar. Britain said Royal Marines had assisted in the capture of the ship because the oil was bound for Iran’s close ally Syria, in breach of an EU embargo. Iran has promised to retaliate against the British, but some of its former officials are said to be in Gibraltar trying to negotiate the ship’s release.

Ayatollah Ali Khamenei, Iran’s supreme leader, said on Tuesday: “Evil Britain commits piracy and steals our ship ... and gives it a legal appearance. The Islamic Republic ... will not leave this wickedness unanswered and will respond to it at an appropriate time and place.”

The UK foreign secretary, Jeremy Hunt, said at the weekend he was willing to release the ship if there were guarantees the oil would not be sent to Syria. European support for the seizure of the Grace 1 has been sparse, with some questioning the wisdom of opening up a new front with Iran at such a sensitive moment.

Iran’s foreign minister, Javad Zarif, speaking in New York, criticised Britain as he pointed out that Iran was not under EU sanctions and was entitled to sell oil to any country not subject to UN sanctions.

Iran’s unravelling nuclear deal with world powers has led to increased tensions in the Gulf region after the US pulled out last year and reimposed economic sanctions.

The US has sent advanced fighter jets and thousands of extra troops into the Middle East while mysterious attacks on oil tankers and the shooting down of a US military surveillance drone by Iran have added to the fears of an armed conflict breaking out. The UK said on Tuesday it was sending a third frigate to the region, but that the decision was not linked to the Gulf crisis.

Khamenei has for the first time warned that Tehran would continue removing restraints on its nuclear programme. The supreme leader accused Britain, Germany and France of failing to uphold their obligations under the 2015 nuclear deal between Iran and the west.

Play Video 0:36 Jeremy Hunt says 'small window' exists to save Iran nuclear deal – video

“We abided by our commitments and even beyond them. Now that we’ve begun to reduce our commitments, they oppose it. How insolent! You didn’t abide by your commitments! We have started to reduce our commitments and this trend shall continue,” he said.

International Atomic Energy Agency inspectors confirmed last week that Iran was enriching uranium to 4.5% fissile purity, above the 3.67% limit set by the nuclear deal, a second breach in as many weeks after Tehran exceeded limits on its stockpile of low-enriched uranium.

But in a potential sign of flexibility about a future talks agenda with the US, Zarif for the first time said Iran would discuss its ballistic missile programme on condition that the US stopped selling weapons to Saudi Arabia and the UAE. In an interview with NBC, he said: “So if they want to talk about our missiles, they need first to stop selling all these weapons, including missiles, to our region.”

The US secretary of state, Mike Pompeo, welcomed Zarif’s statement.

Economic sanctions imposed on Iran since the 1979 Islamic Revolution have cut into its ability to buy advanced weaponry abroad. It relies on pre-1979 US fighter jets and ageing Soviet MiGs, and has instead invested heavily in its ballistic missile programme.

Khamenei has reportedly restricted the range of ballistic missiles manufactured in Iran to 1,240 miles. While that keeps Europe out of range, it means the missiles can hit much of the Middle East, including Israel and American military bases in the region.