Lindsay and Craig Foreman were detained seven months ago on espionage charges while on global motorbike trip

A British couple detained in Iran for seven months on espionage charges have been moved to separate prisons in and near Tehran, heightening fears for their welfare, their son said on Monday.

Lindsay and Craig Foreman, both 52 and who previously split their time between south-east England and Spain, were seized in Kerman, in central Iran, in early January while on a round-the-world motorbike trip.

Their family have known little about their whereabouts since then, but say they learned on Sunday via the Foreign Office that Lindsay has been transferred to Qarchak women’s prison near the capital.

Human rights groups have repeatedly criticised the dire conditions reported there.