BRITAIN should be "scared" about Tehran's retaliation over the dramatic seizure of an Iranian supertanker by Royal Marines, a firebrand cleric warned today.

Mohammad Ali Mousavi Jazayeri hinted the Islamic Republic may strike back over the capture of the giant vessel, impounded over fears it was illegally shipping oil to Syria.

"I am openly saying that Britain should be scared of Iran's retaliatory measures over the illegal seizure of the Iranian oil tanker," said the cleric, a member of the powerful clerical body the Assembly of Experts.