British MP Amber Rudd has resigned from Prime Minister Boris Johnson's cabinet.
The UK Work and Pensions Secretary made the move after 21 Tory MPs were expelled from the party this week.
It comes just two days after the prime minister's brother Jo Johnson resigned.
In a tweet she said: "I have resigned from Cabinet and surrendered the Conservative Whip.
"I cannot stand by as good, loyal moderate Conservatives are expelled. I have spoken to the PM and my Association Chairman to explain. I remain committed to the One Nation values that drew me into politics."
I have resigned from Cabinet and surrendered the Conservative Whip.
— Amber Rudd (@AmberRuddUK) September 7, 2019
I cannot stand by as good, loyal moderate Conservatives are expelled.
I have spoken to the PM and my Association Chairman to explain.
I remain committed to the One Nation values that drew me into politics. pic.twitter.com/kYmZHbLMES
She told the Sunday Times her decision came as she believes there is “no evidence” Mr Johnson is really seeking a deal with the European Union.
Mr Johnson’s office said she knew she would have to sign up to potentially leaving the EU with no-deal when she took on the job in his cabinet.
“We are disappointed to learn that Amber has chosen to leave government and the party,” a spokesman for 10 Downing Street said in a statement.
“She was a talented welfare minister but all ministers who joined joined cabinet signed up to leaving the EU on October 31 come what may, delivering on the referendum result as the public were promised. That has not changed.”
She told the Sunday Times said she planned to fight the next election as an “independent Conservative” and away from her current seat of Hastings & Rye, on the southern coast, where she has a majority of just 346.
Mr Johnson's brother resigned on Twitter two days ago.
He said: "In recent weeks I have been torn between family loyalty and the national interest.
"It's an unresolvable tension."
The resignations come after a group of 21 Conservative MPs, who voted against the government by supporting a bill to stop Britain leaving the EU without a deal, were expelled.
The rebel MPs were removed from the party by the prime minister in a move that has faced heavily criticised.
The leader of the Commons, Jacob Rees-Mogg, confirmed on Thursday the government would table another motion to hold a general election, after its first attempt was defeated on Wednesday.
It comes after Mr Johnson lost all three of the key votes in Parliament since he became leader.
But on Thursday he reiterated his determination to deliver Brexit saying he'd “rather be dead in a ditch” than agree to another delay.
