Labour former home secretary Lord David Blunkett has said that the resignation of veteran MP Frank Field means the party faces “irrelevance” unless the situation is not used as a “catalyst for seismic change”.

Lord Blunkett insisted the veteran Birkenhead MP’s decision to quit the Labour whip called for a rethink of the “Corbyn project”.

Writing in the Daily Telegraph, Lord Blunkett said: “Frank Field’s decision, and his concerns over both anti-Semitism and the behaviour of party members indicate a deeper malaise.

“His actions need to be seen as a catalyst for seismic change and a rethink of the so-called ‘Corbyn project’.

“The commitment to Labour as a ‘broad church’, which motivated some of those who nominated Jeremy, has been thrown back in their faces and demonstrated that the so-called ‘new style of politics’ is anything but.

“Quite simply, Labour has to put its own house in order as decisively and speedily as possible.

“What matters for the health of our democracy and the continuity of the existence of the Labour party, of which I have been a member for 55 years, are the actions taken and the quality of leadership from Jeremy Corbyn and his colleagues over the next seven days.

“Either Jeremy Corbyn can lead a party into gradual decline and irrelevance, or demonstrate that he can lead a party fit for government. The choice is his.”

The comments came as Field said he will employ “the best legal minds” to dispute party rules which say he cannot return to the party after resigning the whip.

Field, who has served as the MP for Birkenhead for almost 40 years, was told by party chief whip Nick Brown that his decision to resign automatically meant he was no longer a member.

Labour sources confirmed that by resigning the whip Field had “automatically opted to resign from the Labour Party”.

Field told the Press Association that he would be making a legal challenge against the move.

He said: “It was a very friendly meeting, he’s a good colleague, but the sad bit of news in it was that he thought the Labour Party rule book was clear, that if I resign the whip I couldn’t be a Labour Party member.

“I told him I was sorry to hear that obviously, that I would actually get the best legal minds I could on the job and that I would dispute that.”

The one-time minister for welfare reform, who was charged by Tony Blair to reform the welfare state by “thinking the unthinkable”, sensationally resigned saying that the party was now governed by “a culture of intolerance, nastiness and intimidation”.

In an interview with the Press Association he said: “It’s been a pretty big and tiring step that I’ve taken, I don’t regret it, I think it is important.

“I’m not a gesture politician, I do this, I hope with others, to effect change and I think that process has actually started on this.

“The people of Birkenhead are sovereign in this matter, I would hope that providence willing, to be the Labour candidate next time.

“If not I will be the Independent Labour Party next time.”

Field said the saga was “one of the saddest” in his long career.

The longstanding Labour man added that talk of a by-election was “another game, for another day”.

He earlier stressed his resignation of the whip over the anti-Semitism crisis was not part of a plot to bring down the Labour leader.

“I hope and I believe Jeremy will lead us into the next election and it is not true I’m a constant critic of Jeremy,” Field said.

“That isn’t true. I believe he has the right to take us into the next election because he has won two leadership contests.

“The idea this is part of a plot or anything else is simply crazy. It is because I think he will lead us into the next election that I think these issues are urgent.”

However, Field added that he felt Corbyn’s thanks for his service was “as though I was resigning from a whist club” and pointed out that he had been a member of Labour longer than his leader.

The Birkenhead MP also denied claims that he was jumping before he was pushed, having lost a no-confidence vote within his constituency Labour party after backing Brexit.

He said: “I have been through all this before when I have been deselected and I am still the Labour party candidate.

“I wish to be the Labour party candidate at the next election and, if I am not, I shall stand as an independent Labour candidate.

“The people who decide this are not a small caucus of 30-odd people but the 70,000 electors of Birkenhead.”

Responding to claims by Labour MP Chris Williamson that he had made “grotesque slurs with no basis in reality” about bullying within his constituency Labour Party that had been “previously resolved”, Field was scathing.

“If they have investigated it and concluded it is all fictitious they have never told me,” he said.

“I have been writing and copying in the chief whip saying this is still going on, this is new material for you.

“It is just untrue for an unknown Labour Party spokesman to say that.”