Due to rising tensions with the US, Iran captures third oil tanker from the Persian Gulf

Iran claims it has seized a third foreign oil tanker in the Gulf in a further escalation of tensions between Tehran and Washington and its regional allies, who continue to stare each other down over crippling economic sanctions imposed by the Trump administration.

Iranian state media claimed the tanker was Iraqi and was seized on Wednesday in a northern part of the strait of Hormuz with a cargo of 700,000 litres of oil bound for neighbouring Arab states. The strait is one of the world’s most important waterways, on which a combustible standoff has played out since early July, when a British warship intercepted an Iranian tanker off the coast of Gibraltar.

Global shipping companies had not reported a tanker missing in the Gulf, in contrast to the furore that surrounded Iran’s seizure of the British-flagged ship Stena Impero last month, or the explosions that hulled four other tankers in the weeks before. Iranian-backed television in Lebanon broadcast footage of what it claimed was the latest seizure. Tehran and Baghdad maintain a close relationship and the implications of an Iraqi ship being seized by an ally were not immediately clear. The tanker shown in the footage was smaller than those caught up in earlier attacks. The claims could not be independently verified.

It is understood the UK’s Department for Transport has tracked all of the British-flagged tankers in the region and all are accounted for. It is not thought there are any British nationals onboard or that the ship’s cargo is linked to Britain.

Iranian officials claim the ship’s cargo was transferred to Iran’s Bushehr province, and onwards to the National Oil Distribution Company.

Leaders of Iran’s Revolutionary Guards have explicitly linked the seizure of the Stena Impero and its crew to the capture of the Iranian vessel, Grace 1, which Britain and the US claim was smuggling fuel to Syria. The seizure came amid a campaign of “maximum pressure” designed to diplomatically isolate Tehran and cripple its oil-dependent economy.

The stated US aim of tightened economic sanctions, which were reimposed in May, is to force Iran to renegotiate the nuclear deal signed between both countries in 2015, but which Donald Trump withdrew from last year. That deal lifted a sanctions regime and allowed Iran to renew international oil trading in return for it agreeing not to enrich uranium – an essential component of a nuclear weapons programme, which its leaders had long been accused of secretly building.

In the wake of Washington reneging on the deal, Iran has vowed to resume uranium enrichment and to continue trading oil, on which its increasingly vulnerable economy depends.

The latest seizure comes days after the US imposed sanctions on Iran’s foreign minister, Javad Zarif – the official who negotiated the nuclear deal with the Obama administration. The unusual move to sanction a global diplomat removes from the table the only senior Iranian official with whom senior US diplomats are familiar, and appears to place further obstacles in the way of a diplomatic solution to the crisis, which regional observers insist has the potential to spill over into a devastating war.

Iranian officials have told regional counterparts that they believe the US president is prepared to act on his bellicose rhetoric to attack the country. The US has sent a small number of troops to neighbouring Saudi Arabia in the wake of the escalation in tensions, and Britain has pledged to escort all British tankers through the strait of Hormuz. US efforts to coerce European states to do the same have met a lukewarm reception, and Iran has warned against the use of naval escorts.

Intelligence officials say a rise in proxy campaigns across the region, rather than a direct clash between Tehran and Washington, is a more likely outcome in the coming weeks. However, three officials who spoke with the Guardian cautioned that the potential for miscalculation remained high.

The United Arab Emirates, which shares the strait with Iran, said on Friday that it and neighbouring Saudi Arabia, two regional foes, preferred a diplomatic resolution to the crisis. The UAE last week arranged a meeting between officials from the Iranian coastguard and its own forces.