Iranian Prime Minister Hassan Rouhani hinted about a possible exchange with the U.K.-flagged ship it seized on Friday in the Strait of Hormuz in exchange for Great Britain giving back an Iranian oil tanker it captured earlier this month off Gibraltar.

“We do not seek the continuation of tension with some European countries,” he said on Wednesday via his website. “Should they be committed to international frameworks and give up their wrong actions, including what they did in Gibraltar, they will receive a proportional response from Iran.”

Last week, Iran seized two U.K.-owned oil tankers: the Liberian-flagged MV Mesdar and the U.K.-flagged Stena Impero.

The Stena Impero, which had 23 crew members onboard, “was approached by unidentified small crafts and a helicopter during transit of the Strait of Hormuz while the vessel was in international waters,” according to Stena Bulk and Northern Marine Management, which later added “that everyone was safe with good cooperation with the Iranian personnel onboard.”

Each side has labeled the seizure of one another’s ships as “hostile acts” and “piracy.”