Resignations are over Brexit and other differences
An eighth Labour MP, Joan Ryan, and three Tory MPs, Anna Soubry, Sarah Wollaston and Heidi Allen, have quit for the Independent Group.
On Monday, Chuka Umunna, Luciana Berger, Chris Leslie, Angela Smith, Mike Gapes, Gavin Shuker and Ann Coffey quit the Labour party today and form a Parliamentary coalition.
The Labour MPs cite Brexit and antisemitism as reasons for their departure, while the Tory MPs also cite Brexit and the party's "lurch to the right".
Speaking about her resignation at a press conference announcing the decision, Ms Berger said that Labour had become "institutionally antisemitic" and she was "embarrassed and ashamed" to stay.
In a statement written in response to the mass resignation, Jeremy Corbyn said: ”I am disappointed that these MPs have felt unable to continue to work together for the Labour policies that inspired millions at the last election and saw us increase our vote by the largest share since 1945.”
And Shadow Chancellor John McDonnell said the "honourable thing for them to do" would be to stand down and fight by-elections.
He added: "We shouldn't splinter in this way. It is better to remain in the party, fight your corner."
The MPs, who all back a second referendum on the UK's EU membership, will sit in Parliament as the Independent Group, rather than form a new political party.
Chuka Umunna said they had urged other Labour MPs and members of other parties to join them. He also confirmed there would that the new group would not merge with the 11 Liberal Democrats MPs, and the group wanted to "build a new alternative".
The group's website says: "The Conservatives are captured by their right-wing, Labour by their hard left, and all put their own party interests before what is best for the country.
"It’s time we changed our old-fashioned politics for politics fit for the 21st century."
The seven MPs took turns to explain their reasons for quitting Labour.
Ms Berger said: "I am leaving behind a culture of bullying, bigotry and intimidation. I look forward to a future serving with colleagues who respect each other."
Chris Leslie said Labour under Mr Corbyn had been "hijacked by the machine politics of the hard left".
Mike Gapes said: "I am sickened that Labour is now perceived by many as a racist, antisemitic party."
He added that it was "increasingly clear that prominent figures in the Corbyn Labour leadership do not want to stop Brexit."
Laura Parker, national coordinator of grassroots Labour group Momentum, said the seven MPs want to "take us back to the politics of the past" and the "Blair years programme of privatisation, tax cuts for the rich and deregulation of the banks".
She added: "They offer no concrete solutions, no new ideas and have no support amongst the public."
Former Labour leader Ed Miliband said he "deeply regrets" the decision the MPs took and London Mayor Sadiq Khan said it is a "desperately sad day".
Liberal Democrat leader Sir Vince Cable said the split was "not unexpected, or unwelcome," adding that his party is open to "working with like-minded groups and individuals in order to give the people the final say on Brexit, with the option to remain in the EU."
Conservative Party Chairman Brandon Lewis said the resignations confirm that Labour "has become the Jeremy Corbyn Party – failing to take action on everything from tackling anti-Jewish racism to keeping our country safe."
And former UKIP leader Nigel Farage, whose new Brexit Party launched earlier this year, tweeted: "This moment may not look very exciting but it is the beginning of something bigger in British politics – realignment."
What the TSR community thinks
In a TSR thread about the resignations, Drewski said: "I'd like for this to be the beginning of a new movement, but far, far, far too many people in this country will simply vote Labour or Conservative regardless of who's in the seat. In a lot of constituencies in this country you could have a potato with the right coloured rosette on it and it would get elected as an MP. Until we change that, this movement is doomed."
Decahedron said: "There have been rumours circling for weeks about this, but given how Berger has been treated as of late it doesn't come as much surprise. It is far more telling that Corbyn won't even recognise that his party as an antisemitism problem."
But Razzzberries said she was "shocked" by the news.
Plagioclase said: "They may get nowhere but can you really blame them? The Labour leadership is currently complicit in an aim that goes against everything the party ought to be standing for and shows no real sign of changing its mind. I am very sympathetic to these MPs."
But Fullofsurprises questions the approach, saying: "To me they just seem behind the curve. Luciana and Chukka in particular are/were key Blairites (they were both favoured by Tony and talked of as possible successors) and they seem not to have accepted that the public, more than Labour itself, decisively dumped Blairism."