Boris Johnson's office has slammed Vince Cable for "peddling lies" about him being poised to resign amid growing tensions in the Cabinet over Brexit.
The newly annointed leader of the Lib Dems claimed a "civil war" had erupted between international trade secretary Liam Fox and chancellor Philip Hammond over plans for a transitional agreement.
“There is no cabinet consensus for moderation,” Cable said. “And the rumours of Boris Johnson being about to resign fuel the uncertainty.”
A Foreign Office spokesman hit back, saying: "Vince Cable is making his stuff up and maybe he should take more time to think up some policies rather than wasting his time on peddling lies.
"Boris and Philip Hammond are working closely to take the the UK out of the EU and are not going to be diverted from that important task."
But Cable would not leave the argument there.
“If the foreign secretary is working so closely with the chancellor, can he confirm that he supports the chancellor’s call for a three-year transitional deal with continued free movement of labour? So far he has been uncharacteristically silent on the subject," he retorted.
“It is certainly bold of Boris Johnson to accuse others of lying. How is he getting along with finding that £350m a week extra he promised the NHS?”
Johnson has yet to comment publicly on Hammond’s transitional plans. However, he has previously gone off message to claim there is no plan for a "no deal" scenario, as well as telling the EU to go whistle for its "extortionate" divorce bill.