LABOUR'S biggest funder has hit out after Sir Keir Starmer sacked his shadow transport minister in a row over an RMT picket line.

Unite said the decision to send Sam Tarry to the backbenches showed that the party were becoming "more and more irrelevant to ordinary working people."

Sir Keir had urged his frontbenchers to stay away from the industrial action on Tuesday, but Mr Tarry joined striking workers outside Euston station in London and gave a number of interviews to broadcast media.

A spokesman for the party claimed that Mr Tarry was not sacked because he stood on the picket line, but because he appeared on TV without permission and did not speak to an "agreed frontbench position."

During an interview with Sky News - in which he also mistakenly referred to himself as the shadow secretary of state for transport - he claimed it was “not acceptable to offer below inflation pay rises.”

Labour’s position is that it is for ministers and unions to negotiate terms.

A spokesman said: “The Labour party will always stand up for working people fighting for better pay, terms and conditions at work.

“This isn’t about appearing on a picket line. Members of the frontbench sign up to collective responsibility. That includes media appearances being approved and speaking to agreed frontbench positions.

“As a government in waiting, any breach of collective responsibility is taken extremely seriously and for these reasons, Sam Tarry has been removed from the frontbench.”

Sharon Graham, the General Secretary of the Unite union, accused the party of indulging in "old factional wars."

She said: "The Labour party sacking of Sam Tarry for supporting working people on strike, against cuts to their jobs and pay, is another insult to the trade union movement.

"Quite frankly it would be laughable if it were not so serious.”

She added: “At a time when people are facing a cost of living crisis and on the day when the Conservative government has launched a new wave of attacks on the rights of working people, the Labour party has opted to continue to indulge in old factional wars.”

Ms Graham continued: “Labour is becoming more and more irrelevant to ordinary working people who are suffering. Juvenile attacks on trade unionists will do absolutely nothing to further Labour’s prospects for power."

Unite pays around £1m in affiliation fees to Labour every year.

Mr Tarry's sacking was criticised by many in the party, including in Scotland where a number of the party's MSPs joined the picket line.

MSP Carol Mochan questioned Sir Keir's decision: "Call me old fashioned but shouldn’t Labour Transport Ministers be standing up for transport workers?" she tweeted.

Her Holyrood colleague Monica Lennon accused Sir Keir of running away from "promoting the rights and interests of workers."

MP Ian Lavery called the decision "shameful."

John McDonnell, the former shadow chancellor, said Mr Tarry was "the first Labour MP to be removed from his frontbench position for joining a trade union picket line to support workers."

Responding to his sacking by Sir Keir, Mr Tarry - who is the partner of deputy leader Angela Rayner - said: “As a Labour politician, I am proud to stand with these striking rail workers on the picket line in the face of relentless attacks by this Tory government.”

He added: “It has been a privilege to serve on Labour’s frontbench for the past two years and to have had the opportunity to speak up for hard-pressed workers who deserve so much better than the treatment they’ve received from this corrupt and out-of-touch government.

“I remain committed to supporting the striking rail workers, and campaigning for a Labour victory at the next general election, which I will fight for relentlessly from the backbenches.”

Mr Tarry is facing a deselection battle in his Ilford South constituency after local members voted against him automatically becoming their candidate at the next election.

He will instead have to see off a challenge from other hopefuls.

The situation is messy as Mr Tarry has claimed the decision to move to an open ballot was only achieved through rule-breaking and voter fraud.