TEHRAN, Iran (AP) — Iran’s president said Wednesday that Britain will face “repercussions” over the seizure of an Iranian supertanker last week that authorities in Gibraltar suspect was breaching European sanctions on oil shipments to Syria.

Hassan Rouhani was quoted by the official IRNA news agency as calling the seizure “mean and wrong” during a Cabinet meeting. “You are an initiator of insecurity and you will understand its repercussions,” he warned the British government, calling for the “full security” of international shipping lanes.

The tanker’s detention comes at a particularly sensitive time as tensions between the U.S. and Iran grow over the unraveling of the 2015 nuclear deal, from which President Donald Trump withdrew last year. In recent weeks, Iran has begun to openly breach limits on uranium enrichment set by the deal in order to pressure European signatories to salvage it.

Foreign Minister Mohammad Javad Zarif meanwhile denied the supertanker belonged to Iran, saying whoever owned the oil shipment and the vessel could pursue the case through legal avenues. Iran had earlier summoned the British ambassador over what it called the “illegal interception” of the ship.

The latest U.S.-Iranian tensions date back to last year, when Trump withdrew from the nuclear accord and restored heavy sanctions on Iran, including its oil industry, exacerbating an economic crisis that has sent the currency plummeting.