The detained British-flagged tanker Stena Impero was in an accident with an Iranian fishing boat and ignored its distress call, Iran's Fars news agency reported today, quoting an official.

All 23 crew on the tanker were now at Bandar Abbas port and would remain on the vessel until the end of an investigation, Fars quoted the official as saying.

"It got involved in an accident with an Iranian fishing boat... When the boat sent a distress call, the British-flagged ship ignored it," the head of Ports and Maritime Organisation in southern Hormozgan province, Allahmorad Afifipour, told Fars.

"The tanker is now at Iran's Bandar Abbas port and all its 23 crew members will remain on the ship until the probe is over."

The crew was made up of 18 Indian nationals and five others from Russia, the Philippines, Lithuania and elsewhere, Afifipour said.

The Stena Impero was taken to Bandar Abbas on Friday night by the naval forces of Iran's Revolutionary Guards and the investigation into the accident began today, Afifipour said, according to Fars.

Britain said earlier it was urgently seeking information about the tanker, which had been heading to a port in Saudi Arabia and suddenly changed course after passing through the strait at the mouth of the Gulf.

Already strained relations between Iran and the West have become increasingly fraught since the British navy seized Iran’s Grace 1 tanker in Gibraltar on July 4 on suspicion of smuggling oil to Syria in breach of EU sanctions.