The parliamentary watchdog has launched an investigation into allegations that the pensions minister, Paul Maynard, used his taxpayer-funded constituency office as a Conservative campaign office. The investigation by the Independent Parliamentary Standards Authority (Ipsa), which oversees expenses, follows reports that Maynard charged taxpayers when producing political materials. The MP for the marginal constituency Blackpool North and Cleveleys has said he will cooperate fully with the investigation, which has already been subject to a six-week assessment by Ipsa. Rishi Sunak already faces the prospect of a byelection in neighbouring Blackpool South after an independent panel this week upheld a 35-day suspension of Scott Benton, formerly a Tory MP, for offering to lobby ministers on behalf of the gambling industry. The Sunday Times reported in January that Maynard had claimed rent for an office that serves as his local party headquarters. It also alleged breaches including producing overtly political materials promoting the Conservatives and efforts to seek his re-election. Concerns were said to have been raised in summer 2022 by a member of the MP’s local Conservative association. The Sunday Times reported that the member had come forward after trying to raise alarm bells with the party. It published what it said was a recording of the member raising her concerns at a meeting, where Maynard could be heard saying: “Why are you trying to solve a problem we don’t have?” Confirming its investigation on Thursday, Ipsa said it would seek to determine whether the MP “has been paid an amount under the MPs’ scheme of staffing and business costs … that should not have been allowed”. The Liberal Democrats are calling on Sunak to withdraw the Conservative whip from Maynard while the “extremely serious” allegations are investigated. Maynard, who entered parliament at the 2010 general election and was previously a speechwriter and adviser for William Hague and Liam Fox, has been pensions minister since last November.