British Foreign Ministry is seeking Kamal Foroughi's immediate release on medical grounds. (Representational Image)
Britain's foreign ministry has said it is seeking the release of a British-Iranian citizen from jail in Iran, where he has been held for four years on espionage charges.
Kamal Foroughi, 76, was arrested in 2011 while working in Tehran as a business consultant, his son Kamran said. His arrest was first reported by the Guardian newspaper in October this year, when Foroughi's family decided to break their silence.
The revelation came amid a renewed crackdown on dissent in Iran, which analysts said has intensified since Supreme Leader Ayatollah Ali Khamenei warned in September of Western "infiltration" in the Islamic Republic.
A British foreign ministry spokesman said on Wednesday that Foreign Minister Philip Hammond had raised the case with Iranian officials, including President Hassan Rouhani, and that Britain is seeking Foroughi's immediate release on medical grounds.
He added that British diplomats have been unable to provide Foroughi with consular assistance because Iran does not recognise dual nationality. Britain reopened its embassy in Tehran in August, four years after protesters stormed the compound.
Iran has not confirmed Foroughi's arrest or publicly commented on the case. Iranian foreign ministry officials were not immediately available for comment.
Foroughi is the only British citizen known to be currently held in Iran. Several US citizens have been detained and jailed on espionage charges.
Iranian-American businessman Siamak Namazi was arrested when visiting relatives in Tehran in October, and Nizar Zakka, a Lebanese citizen with US residency, disappeared in September after attending a conference in Tehran. The state broadcaster later said he had been arrested.
Last month, the judiciary said Washington Post journalist Jason Rezaian had been sentenced to jail on espionage charges. Former US marine Amir Hekmati and Christian pastor Saeed Abedini are serving jail terms, while Robert Levinson, a former FBI investigator, disappeared in Iran in 2007.
On Tuesday, the US State Department said it was aware that another US citizen, Hamid Samiee, had been detained in Iran. It said it was investigating the case and could not confirm reports that he had been executed.
© Thomson Reuters 2015