Labour leader Keir Starmer is coming under growing pressure from senior party figures and activists to hold Boris Johnson to account over the disastrous effects of his Brexit deal on many UK businesses. After more than six weeks of virtual radio silence on Brexit, the Labour leader has yet to make a sustained challenge of any sort to the prime minister on the issue. This is despite hauliers reporting massive falls in trade volumes to the EU and half of 470 UK exporters telling the British Chambers of Commerce in a survey that they are facing real problems. When Johnson announced the limited free trade deal with the EU on 24 December, Starmer made a statement saying Labour would accept the deal to avoid any risk of a no deal outcome. But he insisted it was limited and flawed and that Labour would stop at nothing to expose its shortcomings. “We will hold you to account for it. Every second you are in power. For the promises you have made. And the promises you break,” Starmer said. Since then – despite Johnson having insisted the deal would boost UK trade and that there would no border in the Irish sea – many UK exporters have been driven to take drastic action, either stopping exports to the EU altogether or setting up operations inside the single market, meaning the loss of jobs, investment and tax revenues in the UK. Last night Richard Corbett, a former Labour leader in the European parliament and ex-member of the shadow cabinet, called on Starmer to start exposing the prime minister’s “incompetence and malevolence”. “The idea that the Brexit issue is done and dusted is for the birds,” Corbett told the Observer. “First, because Johnson’s deal is full of gaps that still need to be negotiated including on services and on fisheries. “Second, because where it has settled issues, it has done so badly, as shown by the crescendo of complaints from companies and others including musicians and students. “And third because the government seems intent on seeking conflict with the EU, from threatening to tear up the agreement on Northern Ireland to departing from the level playing field commitments. “Just as with Covid, Labour must highlight Johnson’s incompetence and malevolence, and point to how the damage can be rectified.” Ben Bradshaw, the MP for Exeter and a former Labour cabinet minister, said it was entirely right that Starmer had decided to focus his criticisms mainly on Covid-19. “However,” Bradshaw added: “With the mounting evidence of basic flaws and problems in Boris Johnson’s deal it is not going to be sustainable not to talk about Brexit for very much longer. Otherwise, what is the point of being the opposition?” It is understood that several members of the parliamentary party have relayed their concerns to the leadership about Starmer’s silence on Brexit since the start of the year. As shadow Brexit secretary under Jeremy Corbyn, Starmer was the party’s leading advocate of a second referendum, and warned of the dangers of being outside the single market. But since Johnson struck his deal, tensions have grown. Among those with concerns about Labour backing Johnson’s deal in December was the shadow chancellor, Anneliese Dodds. Many Labour MPs say that Starmer, having ordered his troops to support the deal, fears he would fall into a political trap set by the Conservatives if he now attacked Johnson for its consequences. Labour MPs also say it is clear that Starmer is worried about his party losing the support of more traditional Labour voters who voted for Brexit, if he were to start to criticise the deal that implemented it. At the 2019 general election the Tories took many seats from Labour behind the so-called red wall in the Midlands and north of England, which Starmer knows he will have to win back to have any chance of entering Downing Street. But Labour pro-Europeans say the issues are too important to ignore because of fears of being embarrassed at the dispatch box. Michael Chessum, national organiser for the leftwing Labour grouping, Another Europe is Possible, said: “Again and again, Starmer seems to be going back on his promises. He won the Labour leadership on a cast-iron promise to defend freedom of movement, but last month he announced on live national television that this was no longer his policy. “He has carefully manufactured an image as a principled internationalist – and yet he whipped for the government’s dreadful Brexit deal in December. And when he voted for that deal, he did so promising to hold the government to account on it for every second it was in power, but there isn’t much evidence of that.” A spokesman for Starmer said he was not available for comment on Saturday, and that Rachel Reeves, who has responded to stories about post-Brexit chaos by accusing the government of incompetence, was leading on the issue. The spokesman added: “This government ignored British business during negotiations, gave them a matter of days to prepare for the deal and is now downplaying the challenges exporters are facing. “The Conservatives have wrapped businesses in red tape and higher costs, and put contracts and jobs at risk. Labour will challenge them every step of the way on the implementation of the deal in order to get the best result for the British economy.” In the latest Opinium poll for the Observer, the Tories have stretched their lead to 5pts, to 42% (up 3pts on a fortnight ago) while Labour are on 37% (down 1pt). Boris Johnson maintains his lead on who would be the best prime minister: 32% now select Johnson (-1) while 27% think Starmer would make the best PM (-2); 25% said neither and 16% said they don’t know. On Sunday Labour launches plans to help ease the Covid debt burden faced by firms across the country by setting up a British business recovery agency. While not specifically mentioning Brexit, Dodds says the party’s priority is to “help businesses get back on their feet, secure our economy and get Britain on the road to recovery”. British business is currently weighed down by £71bn of Covid debt through government-backed loans during the crisis – with the chancellor encouraging banks to begin asking for repayments in March. New analysis by Labour reveals that 850,000 businesses are at risk of closure in the next three months, putting 2.4 million jobs at risk. Labour’s plan would ease the debt burden on business, secure the economy and help British business to rebuild with a range of measures including converting the bounce back loans scheme into a “student loan style” arrangement, so that businesses have to start repayments only when they are making money.