Boris Johnson's brother has quit the Government, saying he had been "torn between family loyalty and the national interest".
Jo Johnson, who had been a senior minister attending meetings of his brother's Cabinet, said there was an "unresolvable tension".
He announced on Twitter he was quitting his role as Universities Minister and would stand down as MP for Orpington.
Mr Johnson said: It's been an honour to represent Orpington for 9 years & to serve as a minister under three PMs.
"In recent weeks I've been torn between family loyalty and the national interest - it's an unresolvable tension & time for others to take on my roles as MP & Minister. #overandout"
Jo Johnson is pro-European and has previously called for a second referendum, a position that puts him at odds with the Prime Minister, who has vowed to leave the EU on October 31 with or without a Brexit deal.
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