Britain’s top civil servant has demanded ministers cooperate with his inquiry into the leaking of discussions at the National Security Council.
Cabinet Secretary Sir Mark, who is also the National Security Adviser, is leading the internal inquiry.
He has written to ministers on the council and their special advisers after the Daily Telegraph reported details of a meeting about Chinese telecoms firm Huawei.
It comes amid mounting pressure for a more robust response to the leak and several cabinet ministers have already denied they were involved.
There has been a backlash against the leak, with Culture Secretary Jeremy Wright saying the government cannot rule out the possibility of a criminal investigation.