Matt Hancock is among three MPs who have been placed under investigation by parliament’s standards watchdog. In a move that threatens to reignite allegations of sleaze in the Conservative party, a series of inquiries were launched by the commissioner, Daniel Greenberg. The former health secretary is being looked into over allegations that he broke the MPs’ code of conduct by “lobbying the commissioner in a manner calculated or intended to influence his consideration” of whether a separate breach had been committed. It is a new offence that was added to the latest version of the code, endorsed by MPs in December 2022. Meanwhile, the Blackpool South MP, Scott Benton, is being investigated over the use of his parliamentary email. It comes a week after Benton was caught offering to lobby ministers and obtain early access to a sensitive government report for up to £4,000 a month. Henry Smith, a backbench Tory MP for 13 years, is also being investigated for an alleged breach of the rules on using taxpayer-funded stationery. A spokesperson for Hancock denied any wrongdoing and claimed he was “surprised” by the move. They said: “Far from lobbying the commissioner, Matt wrote to Greenberg in good faith to offer some additional evidence that he thought was not only pertinent but helpful for an inquiry the parliamentary commissioner for standards is currently conducting. “It’s clearly a misunderstanding and Matt looks forward to fully engaging with the commissioner to clear this up.” The letter sent by Hancock contained evidence that he was said to have been uniquely placed to give. There were only two other existing investigations by the standards commissioner, one of which was into whether the former health minister Steve Brine broke lobbying rules. That was triggered when texts from Brine to Hancock and other cabinet ministers were released as part of a leaked cache of messages sent and received by the then health secretary during the Covid pandemic. Anneliese Dodds, the Labour party chair, said the “constant drip-drip of Conservative sleaze” had “become a deluge”. She claimed that Rishi Sunak’s promise to lead a government of professionalism, integrity and accountability at all levels had “been swamped by scandal after scandal” and added: “The British people will rightly look at the Conservatives and wonder why there is always one rule for them, and another for everyone else.” Hancock was stripped of the Conservative whip in autumn 2022 after appearing on I’m a Celebrity … Get Me Out of Here! while parliament was still sitting. Afterwards, he claimed he had been assured by the chief whip that he would be allowed to formally rejoin the Tory parliamentary party again “in due course”, but he still sits as an independent and has said he will stand down at the next general election. The MP for West Suffolk was found by the previous standards commissioner, Kathryn Stone, to have broken the rules by failing to declare a stake in a family company that won an NHS contract. She allowed him to avoid a sanction – as the breach was found to have fallen “at the less serious end of the spectrum” – and instead have the interest added to the official record “in bold italics”. He also committed a “technical” breach of the ministerial code over the handling of the same matter, according to the then prime minister’s ethics adviser, but again faced no penalty. Benton had the whip suspended last week after referring himself to the standards commissioner. He had been caught out by undercover reporters from the Times who were posing as representatives of a fake investment fund, and laughed when revealing how MPs could get away with not declaring hospitality. When video evidence emerged, he said he had ceased contact with the fictitious company after becoming “concerned that what was being asked of me was not within parliamentary rules”.