Two Labour frontbenchers have resigned in protest at the party’s failure to oppose legislation allowing MI5 and police informants to commit crimes, as 34 MPs rebelled over the issue. They included five Labour MPs serving as personal private secretaries. Margaret Greenwood, the shadow schools spokesperson, quit immediately after the early evening vote, joining the shadow financial secretary to the Treasury, Dan Carden, who had resigned earlier in the day. The two were among a handful of leftwingers remaining on Keir Starmer’s frontbench. “I cannot stand by and allow a bill to go through that will profoundly impact on our civil liberties and the environment in which individuals can get together to have their voices heard,” Greenwood wrote in her resignation letter. But the rebellion could have been larger had a second group of leftwing frontbenchers also decided to defy the whip. Instead, after intense lobbying from senior party figures such as the deputy leader, Angela Rayner, they made a “collective decision to stay on the frontbench and use their roles to ensure the left has a stronger voice in future party policy”, according to a source close the group. They included MPs Andy McDonald, Imran Hussain, Rachael Maskell, Cat Smith, Marsha de Cordova, Alex Sobel, Sam Tarry and Charlotte Nichols. They said they were given “clear assurances” by Starmer that the party would campaign on union issues. However, Labour insiders said no specific concessions had been made. Other MPs who did quit were five parliamentary private secretaries – shadow junior ministers – including Navendu Misra and Kim Johnson, both of whom were aides to Rayner, and Rachel Hopkins, Sarah Owen and Mary Foy. Starmer had wanted Labour MPs to abstain on the bill once their amendments were defeated, arguing that statutory regulation of informants’ conduct would have been necessary if the party had been in power. The bill was introduced by the Conservative government after a series of legal challenges had made it necessary to put the existing policy of allowing informants to be a party to criminal activities on a statutory footing. But critics of the covert human intelligence sources bill argued it did not explicitly rule out crimes such as murder, torture or serious sexual offences – and that it could authorise spying by undercover agents or police, including on groups such as trade unions. In a statement released to Tribune magazine, Carden said he had supported the party’s decision to abstain on the bill at its second reading, but felt he must vote against it when it returned to the House of Commons. “As a Liverpool MP and trade unionist, I share the deep concerns about this legislation from across the Labour movement, human rights organisations, and so many who have suffered the abuse of state power, from blacklisted workers to the Hillsborough families and survivors,” Carden said. A Labour spokesperson said: “We are disappointed colleagues have stepped down. They were valued members of Keir’s frontbench and will continue to play an important role in ensuring a Labour government after the next election.” Priti Patel, the home secretary, sought to highlight the Labour divisions: “Once again, Labour has refused to stand up for those who protect our country and keep us all safe. Their leader may have changed, but Labour still can’t be trusted on national security.”