Iran's judiciary chief has urged the United States not to interfere in cases of detained Americans, days after US Secretary of State John Kerry said a jailed Marine should be freed, according to AFP.

Ayatollah Sadegh Larijani's remarks followed the fourth anniversary of Amir Hekmati's imprisonment in Tehran on what Kerry called "false espionage charges". Hekmati was visiting relatives in the Islamic republic when he was arrested.

Larijani, quoted in Iranian media on Tuesday, said Iran examined legal cases "including those accused of spying for America, with absolute composure and dignity, based on duty and procedure. "The judiciary does not need American officials to write prescriptions for it," Larijani said. "Our advice to them is not to hype (such matters) up uselessly."