The UK’s security minister was accused on Tuesday night of being “genuinely irresponsible” after he claimed a British hostage held by Islamic State was still alive.

Senior Whitehall sources said Ben Wallace, the security minister, may have put John Cantlie’s life in jeopardy by commenting on his status.

The source said Mr Wallace had “massively undermined” his own department. Mr Cantlie, a British photographer, was kidnapped six years ago by the Islamic State of Iraq and the Levant (Isil).

His whereabouts and status are not known, according to well-placed sources inside the Government.

But Mr Wallace went off message at a meeting with foreign reporters at the Home Office on Tuesday, insisting Mr Cantlie was alive when asked.

Within hours, the Home Office was urging media outlets to show sensitivity in repeating the claim.

“We do not discuss individual kidnap cases and speculation is unhelpful,” a Home Office spokesman said.