Iran hinted on Wednesday it is open to a tanker swap with Britain as the owners of a UK-flagged ship seized by the Islamic republic expressed hopes for “positive progress” after speaking to its crew.

The seizure of the Stena Impero has been seen as a tit-for-tat move after British authorities detained an Iranian tanker off Gibraltar this month on suspicion it was shipping oil to Syria in breach of EU sanctions.

Read more: Iranian tanker could be released ‘with guarantees’, says UK

“We don't want tensions with some European countries,” Iran's President Hassan Rouhani said in comments to a cabinet meeting posted on his government's website.

In a clear reference to the tense standoff with the British, Rouhani said if they were to “cease the incorrect acts that they have done, including that of Gibraltar, Iran's response would be” appropriate to their actions.

Iran's Islamic Revolutionary Guard Corps seized the Stena Impero on Friday, surrounding it with attack boats before troops rappelled onto its deck from a helicopter.

The oil tanker and its 23 crew have since been impounded at the southern port of Bandar Abbas for allegedly breaking “international maritime rules”.

The owners of the vessel said on Wednesday they had finally been able to speak to the crew of 18 Indians, three Russians, a Latvian and a Filipino.

“Stena Bulk can confirm that we have had direct communication with the crew of the Stena Impero since late yesterday (Tuesday),” the Swedish shipping company said in a statement.

It said “everyone was safe with good cooperation with the Iranian personnel onboard”.

“We do of course appreciate this step... and that this is a first sign that we will soon see more positive progress from the Iranian authorities,” said its chief executive, Erik Hanell.

Duel over drones

Iran's high-seas standoff with Britain comes amid rising hostilities between the Islamic republic and UK ally, the United States.

The arch-enemies have been locked in a battle of nerves since President Donald Trump withdrew the US from a landmark 2015 deal aimed at limiting Iran's nuclear programme and began reimposing sanctions.

Since the Trump administration began a “maximum pressure” campaign against Iran this year, the situation has worsened with drones downed and tankers mysteriously attacked in sensitive Gulf waters.

The Revolutionary Guards on Wednesday denied losing a drone and challenged the Americans to prove Trump's claims they could find it at the bottom of the sea after the US military said it downed an unmanned aircraft last week.

“I officially declare that none of Islamic Iran's drones have been downed,” Guards' Major-General Hossein Salami was quoted as saying on the force's official website.

“If our enemies have any claims on downing Iranian drones, they should show their proof,” he said.

Iran, which last month shot down a US Global Hawk drone that it said had ventured into its airspace, has repeatedly denied it lost any of its own unmanned aerial vehicles.

In reaction to the Iranian denials, Trump insisted on Tuesday that the US downed a drone. “You can see it laying right down on the bottom of that beautiful bed of water,” the US president said in remarks posted on the White House website.

Iran's defence minister Brigadier-General Amir Hatami responded to Trump on Wednesday by saying the Islamic republic had put on display the wreckage of the US drone it shot down.

“If anyone claims that they have downed one of our drones they must show its (wreckage),” Hatami said according to the semi-official ISNA news agency.

Sanctions 'ceasefire'

During the cabinet meeting, Rouhani also said Iran would be open to talks should there be a “ceasefire” in US economic sanctions against the Islamic republic.

“In this regard, some countries are intermediaries, though they themselves say they are not mediators and are just expressing their own views,” said Rouhani.

“There has been correspondence from both sides on this issue and we are continuing this,” the Iranian president added.

Japanese Prime Minister Shinzo Abe visited Tehran in June for talks aimed at defusing tensions between Iran and the US.

Earlier this month French President Emmanuel Macron sent his top diplomatic adviser, Emmanuel Bonne, to Iran “to piece together a de-escalation” strategy.

Both Japan and France have denied acting as intermediaries between Iran and the US.