Labour MPs expressed outrage last night after a local constituency party voted to expel former chief whip Hilary Armstrong from the party for accusing Jeremy Corbyn of a lack of leadership over antisemitism.

The move by the North West Durham party promoted angry responses from Armstrong’s colleagues in both houses of parliament. She served as an MP from 1987-2010 before being elevated to the House of Lords.

Although a local party has no formal power to expel a member on its own, as expulsions can only be ordered by the general secretary, the party’s national disputes panel or the national executive committee (NEC), the move was seen as an example of deepening divisions and ill-feeling between rival factions.

Armstrong, who served as Labour chief whip under Tony Blair, said she was “very sad” to have learned of the decision, which came days after she signed an advertisement accusing leader Jeremy Corbyn of having “failed the test of leadership” over his handling of antisemitism complaints within Labour.

The Labour peer issued a statement saying her local constituency party “used to be a place where differing opinions were respected”. Armstrong added: “This sadly shows how far the party has departed from its roots. I’m not going to shy away from demanding that the party leadership take real and decisive action to rid antisemitism from the Labour party.”

The controversial full-page advert, published in the Guardian on Wednesday, criticised Corbyn for allowing a “toxic culture” to “divide our movement” and said the party was no longer a “safe place” for its members and supporters. It was signed by 67 Labour members of the House of Lords, including former cabinet ministers Peter Hain and Peter Mandelson, and followed a damning report by BBC’s Panorama programme into the party’s handling of allegations of antisemitism.

A day after it appeared, senior Labour peer and shadow Brexit minister Dianne Hayter was sacked for saying Corbyn was leading the party with a “bunker mentality” similar to the “last days of Hitler”.

On Friday the shadow justice minister, Gloria De Piero, quit the Labour frontbench and announced she would not be standing at the next general election, citing the party’s “lack of tolerance”. The former BBC journalist, who has been the MP for Ashfield in Nottinghamshire for nine years, told the Observer that, while Jeremy Corbyn had said he wanted a new kind of politics, the reality was that many Labour MPs found themselves being abused by party members on social media and elsewhere.

Hilary is Labour to her marrow and if there is no place for her in it, it is done Anna Turley, Labour MP

De Piero said: “Jeremy was right that we need a gentler, kinder politics. But that’s not always what we have. We all need to listen to each other and respect each other. There is no good alternative to that. Johnson is there for the taking at the next general election. Let’s not blow this by turning in on ourselves. I am lucky enough to have the most supportive party any MP could wish for, but I see aggressive language being used against some of our best MPs. The only deselections we need to be focused on is Tory MPs at the next election.”

News of the move against Armstrong in the constituency she served enraged MPs. Redcar Labour MP Anna Turley tweeted: “If this is true it is disgraceful.” She added: “Hilary has served the Labour party with commitment & distinction for decades, as a former social worker, particularly for the vulnerable. She is Labour to her marrow and if there is no place for her in it, it is done.”

Sunderland Central MP Julie Elliott said the move was “astonishing”, and praised Armstrong’s long and loyal service. “Hilary Armstrong has done more for the Labour party than anyone I know, supported women to become active and get elected – she is Labour to her core, has true Labour values. I am proud to call her a friend – words fail me.”

A Labour party spokesman said: “The vote has no formal standing, only the party’s national constitutional committee has the power to expel,” and added that Laura Pidcock MP was not involved in the motion and abstained.

The latest developments came ahead of meetings of the parliamentary Labour party, the shadow cabinet and the NEC this week at which the antisemitism row is due to be discussed. Deputy leader Tom Watson has tabled a motion to the NEC calling for an independent complaints procedure to be set up. On Saturday some senior figures said they were mystified as to why Watson’s motion had not appeared on copies of the NEC agenda, and feared there would be an attempt to put the discussion off.

Separately the Jewish Labour Movement wrote to all members of the shadow cabinet saying it was “heartbreaking” that the issue of antisemitism had to be discussed at all. Mike Katz, the JLM’s national chair, said it was now up to shadow cabinet members to take action. “Whilst the NEC provides the administrative leadership of the party, you, the shadow cabinet, provide its political leadership. We are sorely in need of real leadership on antisemitism, having lacked any up to this point. This is your chance to lead.”