Penny Mordaunt was missing in action while working with Lord Frost to such an extent that he often did not know where in the country she was, friends of the former chief Brexit negotiator have claimed.
It comes as foreign secretary Liz Truss faces accusations of “black ops” in an increasingly bitter row over attacks on the trade minister in the Tory leadership contest.
Leading Truss supporters, including Lord Frost, have suggested Ms Mordaunt is unfit to be prime minister.
Lord Frost told Talk TV he was “quite surprised” she was in second place in the race, behind the frontrunner Rishi Sunak.
“She was my deputy – notionally, more than really – in the Brexit talks last year,” he said. “I felt she did not master the detail that was necessary in the negotiations last year. She wouldn’t always deliver tough messages to the European Union when that was necessary.”
He added: “She wasn’t fully accountable, she wasn’t always visible. Sometimes I didn’t even know where she was. This became such a problem that, after six months, I had to ask the Prime Minister to move her on and find somebody else to support me.”
Friends of Lord Frost said that it got so bad that on occassion he did not know where in the country she was.
One said: “He just did not know where she was, she was missing in action. At one point they had contact once a week over Google Teams, with Ms Mordaunt’s screen turned off, meaning it was difficult to tell her location.” They added that he felt compelled to speak out because MPs who had put her in second place in the leadership race knew so little about her.
Lord Frost is expected to endorse Ms Truss in the coming days.
The attacks were condemned by David Davis, the former cabinet minister who is backing Ms Mordaunt.
“Somebody gets ahead (in the race) and looks to be the real challenger and then the black op starts, the incoming fire starts,” Mr Davis said.
Asked about what Lord Frost said on TV a source from the Mordaunt campaign said: “Penny has nothing but respect for Lord Frost. He did a huge amount to assist our negotiations until he resigned from government. “Penny will always fight for Brexit and always has.“
The campaign has been approached for comment about the latest allegations.
