Brent North MP Barry Gardiner has resigned from the Government after publicly criticising under-fire Prime Minister Gordon Brown.
The MP for Brent North stepped down from his post as Mr Brown's special envoy for forestry on Saturday - as the divided Labour party continued to spiral out of control.
Last Friday, Mr Gardiner had joined the growing list of MPs calling for a leadership challenge, slamming the Prime Minister and claiming the nation had stopped listening to him.
He said: "I was one of those who nominated Gordon last year, and I was very hopeful that he would come in with a very clear vision for the country.
"But unfortunately I don't think he's managed to do that. I think the public have therefore stopped listening to him."
Reports today suggested the rebel MP had been sacked by the Prime Minister.
But he confirmed to the Observer that his resignation letter was emailed to Downing Street on Saturday morning.
Mr Gardiner, who jetted off to New York shortly after the public outburst, joins two other Labour politicians who have left their government jobs after backing a leadership election.
Assistant whip Siobhain McDonagh was sacked for her public criticism of the PM, along with Labour vice-chairman Joan Ryan.
The dismissals prompted Mr Brown to promote Dawn Butler, MP for Brent South, and make her the new assistant whip.
Speaking about the appointment she said: "It is such a privilege to be given a role on a Labour government that has done so much good, but to make history at the same time is pretty awesome.
"Part of my new job will be seeing how the other Labour MPs feel about things in the party and feeding it back to the Government - so it is going to be very important at this time."
Ms Butler was wary to talk about Mr Gardiner's resignation but said she and the majority of the Labour party were 100 per cent behind their leader.
She said: "I think the public are getting tired of all the in-fighting and MPs need to concentrate on what their constituents want.
"Barry sees Labour as the party of the future, with a lot of ideas and policies, but I think he feels it is not selling this vision to the public."