Two of Labour’s most senior figures have admitted the party has lost the trust of some voters over its response to the Israel-Gaza conflict and will have to “engage and listen” to win them back. Rachel Reeves, the shadow chancellor, expressed her regret over people who “couldn’t bring themselves” to back Labour at last week’s local elections, while London mayor Sadiq Khan said the whole party had to regain lost trust. The pair on Tuesday urged against an Israeli offensive in Rafah, with Khan warning such an attack would be a “catastrophe on steroids”. Chief among Labour’s significant local election victories was its narrow win in the West Midlands mayoral contest, with its candidate Richard Parker beating the Conservative incumbent Andy Street. An independent candidate, Akhmed Yakoob, won nearly 43,000 votes there after a campaign focused on Gaza. During the showdown, the party condemned a racist briefing from a Labour source who reportedly said: “It’s the Middle East, not West Midlands, that will have won Andy Street the mayoralty. Once again Hamas are the real villains.” In the wake of the 7 October attacks, when councillors began to quit over the party’s stance, a senior Labour source had been quoted as saying it was a sign the party was “shaking off the fleas”. Khan told the Guardian such comments were “completely unacceptable” and “whoever said those words if they are employed by Labour should be sacked”. Labour is a party of “racial justice, social justice and anti-racism”, he said, adding: “I’m sure if Keir Starmer knew the names of those behind those briefings, he’d kick them out.” Labour failed to regain control of Oxford council, lost control of Oldham council and lost support in Blackburn, Darwen and Bradford. Analysis showed there was an almost 18% drop in the Labour vote in areas of England where more than a fifth of people identified as Muslim. The London mayor managed to buck this trend, gaining the support of Green and Liberal Democrat voters in his historic third-term win. He told the Guardian he was proud of results including a swing towards Labour in areas such as Barnet and Camden, and maintaining support in inner London, areas where there are big Muslim and Jewish populations. Khan championed Starmer and the shadow foreign secretary, David Lammy, for being clear in their criticism of a possible Israeli incursion in Rafah. Asked what would be enough to regain voters’ trust, Khan said: “We’ve got to use Thursday as a reminder of the importance of making the argument across the country. “It’s not about one person, it’s about us as a party engaging with people across the country, listening, responding and being true to our values which is being against what’s happening in Gaza. I’m confident we can regain that trust.” In a Q&A after a speech on the economy in London, Reeves said: “I recognise that there are some people who didn’t vote for Labour last week because they did have concerns – including people in the Muslim community. “I regret whenever someone decides that they can’t bring themselves to vote for the Labour party, and we will seek to rebuild the trust of those communities in the weeks and months ahead.”