As many as 18 Indians, including the captain, are on board the British tanker that Iran’s Islamic Revolutionary Guard Corps seized in the Strait of Hormuz on Friday, AFP reported on Saturday. The other five members of the crew are Filipino, Latvian and Russian.

The Ministry of External Affairs said it was ascertaining further details. “Our mission is in touch with the Govt of Iran to secure the early release & repatriation of Indian nationals,” said the ministry, according to ANI.

Iran’s Islamic Revolutionary Guard Corps had said they seized the tanker for violating international maritime regulations. However, AFP reported that the tanker collided with a fishing boat.

The Stena Impero tanker “was confiscated by the Revolutionary Guards at the request of Hormozgan Ports and Maritime Organisation when passing through the strait of Hormuz, the IRGC said. The tanker was handed over to the organisation for the required legal procedure and investigation, the Revolutionary Guards said.

“The British tanker Stena Impero collided with a fishing boat on its route and, according to law, after an accident it is necessary that the cause of the accident are investigated,” Allah-Morad Afifipoor, director-general of the organisation, said. He added that when the British tanker did not respond to signals from the fishing boat, the crew on the boat informed the ports and maritime organisation.

Stena Bulk and Northern Marine Management, which owns the Stena Impero said the vessel had come under attack by small boats and a helicopter in the Strait of Hormuz. The company added that it was now unable to contact the tanker.

United States National Security Council spokesperson Garrett Marquis condemned the seizure. “The US will continue to work with our allies and partners to defend our security and interests against Iran’s malign behaviour,” Marquis said.

Britain, however, claimed that Iran had captured not one but two ships in the Persian Gulf. “I’m extremely concerned by the seizure of two naval vessels by Iranian authorities in the Strait of Hormuz,” Foreign Secretary Jeremy Hunt said. “These seizures are unacceptable.”

Norbulk Shipping UK, the British owner of the second tanker, said it had been temporarily boarded by armed personnel but was now free to leave. “Communication has been re-established with the vessel and [the captain] confirmed that the armed guards have left and the vessel is free to continue the voyage,” the company said in a statement.

According to the website Marine Traffic, the ship was on its way from China to Saudi Arabia.

United States President Donald Trump on Thursday said a US Navy ship destroyed an Iranian drone in the Strait of Hormuz after the drone came within about 900 metres of the vessel. Iran, however, said it had “no information” about the loss of a drone.

The incident came hours after Iran’s Revolutionary Guards seized a foreign tanker and its crew for allegedly smuggling fuel. It also came amid escalating tensions in the oil-rich Gulf region.

On July 11, the United Kingdom claimed that three Iranian boats tried to impede a British oil tanker in the Gulf. The incident took place while commercial vessel British Heritage was trying to pass through the Strait of Hormuz.