Posted on April 26, 2019
Sir Mark Sedwill 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.
Several cabinet ministers have publicly denied they were involved.
Following Tuesday’s meeting of the council, the Daily Telegraph reported that it had agreed to allow Huawei limited access to help build Britain’s new 5G network, amid warnings about possible risks to national security.
The paper also reported that various ministers had raised concerns about the plan.
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.
Cabinet Secretary Sir Mark is leading the internal inquiry.