Dominic Raab is seen at the Foreign and Commonwealth building after being appointed as the foreign secretary by Britain’s new Prime Minister Boris Johnson in London, July 24, 2019. Photo: Dan Kitwood / Pool via Reuters.

Britain on Thursday ruled out exchanging an Iranian tanker detained by Gibraltar for a British-flagged tanker seized by Iran in the Gulf.

“We are not going to barter: if people or nations have detained UK-flagged illegally then the rule of law and rule of international law must be upheld,” Foreign Secretary Dominic Raab said while on a trip to Bangkok.

“We are not going to barter a ship that was detained legally with a ship that was detained illegally: that’s not the way that Iran will come in from the cold,” he said. “So I am afraid some kind of barter or haggle or linkage is not on the table.”

Tensions have spiked between Iran and Britain since after Iranian commandos seized a British-flagged tanker last month. That came after British forces captured an Iranian oil tanker near Gibraltar, accused of violating sanctions on Syria.