Britain will soon get “slapped in the face” for last week's capture of an Iranian supertanker, a cleric was quoted as saying Friday amid rising tensions between the two nations in the Gulf.

Cleric Kazem Sedghi, an adviser to Iran's Supreme Leader Ayatollah Ali Khamenei, told worshipers during Tehran’s Friday prayer sermon broadcast live on Iranian state TV that the United Kingdom should be worried for their actions off the coast of Gibraltar.

“Iran’s strong establishment will soon slap Britain in the face for daring to seize the Iranian oil tanker,” he said.

IRAN WARNS OF 'REPERCUSSIONS' FOLLOWING 'MEAN AND WRONG' SEIZURE OF OIL TANKER

Sedghi’s warning came after the Iranian government on Friday called Britain to immediately release the oil tanker that British Royal Marines seized last week on suspicious it was breaking European sanctions by taking oil to Syria.

Iran’s Foreign Ministry spokesman accused London of playing a “dangerous game” a day after police in Gibraltar, a British overseas territory on the southern tip of Spain, said they arrested the captain and chief officer of the supertanker.

Abbs Mousavi told Iranian state news agency IRNA that “the legal pretexts for the capture are not valid … the release of the tanker is in all countries’ interest.”

“This is a dangerous game and has consequences,” he added.

BRITAIN'S SEIZURE OF IRANIAN OIL TANKER WON'T GO 'UNANSWERED,' OFFICER SAYS

Gibraltar has insisted its decision to detain the Iranian tanker was taken alone and not on orders from any government, despite a senior Spanish official previously saying the interception was carried out at the request of the United States.

“All relevant decisions in respect of this matter were taken only as a direct result of the government of Gibraltar having reasonable grounds to believe the vessel was acting in breach of established E.U. sanctions against Syria,” Fabian Picardo, the territory’s chief minister, told reporters. “There has been no political request at any time from any government that Gibraltar should act or not act on one basis or another.”

The detained vessel contained 2.1 million barrels of light crude oil, he added.

TRUMP VOWS TO 'SUBSTANTIALLY' INCREASE SANCTIONS ON IRAN IN RESPONSE TO URANIUM ENRICHMENT

The British navy said Thursday it had stopped three Iranian paramilitary vessels from disrupting the passage of a British oil tanker through the Strait of Hormuz, the narrow mouth of the Persian Gulf. The brief but tense standoff stemmed from the U.K.'s role in seizing the Iranian tanker.

On Friday, the British Ministry of Defense said it was moving up its timetable for relieving the HMS Montrose, a frigate operating in the Persian Gulf, with the larger HMS Duncan destroyer in the wake of the recent developments.

"This will ensure that the UK alongside international partners can continue to support freedom of navigation for vessels transiting through this vital shipping lane."

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Iran recently began surpassing uranium enrichment limits set in its 2015 nuclear deal with world powers in response to President Donald Trump's decision to pull the U.S. out of the accord a year ago. He also has re-imposed tough sanctions on Tehran's oil exports, exacerbating an economic crisis that has sent its currency plummeting.

The Associated Press contributed to this report.