MPs Ian Byrne, Dan Carden, Kim Johnson and Paula Barker joined a rally in support of the RMT outside Lime Street station in Liverpool on Saturday.
Addressing the crowd, Mr Byrne said: "It is a privilege to be able to speak today, show my solidarity to the RMT striking membership and thank this magnificent union for everything they have done for our class this week."
He said a photograph of himself and other Labour MPs on a picket line earlier this week, which was published on the front page of the Daily Mail newspaper, now has "pride of place" in his office.
— Liverpool Community Independents (@LIndependents) June 25, 2022
The Liverpool West Derby MP added: "We must use this moment to begin to rebalance the scales of injustice which is waged against the working class.
"This is the moment when the country is saying ‘enough is enough’."
Many waved flags and banners, with one man holding a sign mocking Transport Secretary Grant Shapps.
RMT regional council secretary Darren Pilling told the crowd: “Rail workers are standing up for the kind of pay rise every worker deserves.”
Speakers from other unions also addressed the rally, and there was a performance from the Socialist Singers.
Meanwhile, former Labour leader and independent MP, Jeremy Corbyn joined a picket line at Newcastle Central Station on Saturday.
This morning I joined the @RMTunion picket at Newcastle Central Station to stand in solidarity with striking railway workers defending their jobs, pay and conditions.
Victory for those taking action this week will be a victory for all working people. pic.twitter.com/QmPr5nrxTn
— Jeremy Corbyn (@jeremycorbyn) June 25, 2022
He wrote on Twitter: “This morning I joined the @RMTunion picket at Newcastle Central Station to stand in solidarity with striking railway workers defending their jobs, pay and conditions. Victory for those taking action this week will be a victory for all working people. “
Labour frontbenchers were warned by the leader’s office on Monday not to join picket lines.
Some have ignored the warning so far, including shadow minister Alex Sobel and party whip Navendu Mishra.
His deputy, Angela Rayner said the RMT had been “left with no choice” but to strike earlier in the week and was seen in the wider action in London last weekend.
Labour’s Scottish leader Anas Sarwar joined a picket line in Edinburgh this week to show “solidarity” with the strikers, while Diana Abbott, Beth Winter, and Kate Osborne were also joined picket lines during the week.
Zarah Sultana, Richard Burgeon and former leadership contender, Rebecca Long Bailey were all also seen supporting picketers.
Shadow transport minister Sam Tarry said the RMT’s demands were “legitimate”, adding that there was “nothing militant about standing up for your workers”.