Reform UK MP James McMurdock has given up the whip over allegations against him related to business propriety, the party has said.
Chief whip Lee Anderson said McMurdock, MP for South Basildon and East Thurrock, "removed the party whip from himself" pending an investigation into allegations since published by the Sunday Times.
"At Reform UK we take these matters very seriously and James has agreed to cooperate in full with any investigation," Anderson said.
Reform UK said it would carry out an internal investigation into the allegations.
McMurdock said his business dealings "had always been conducted fully within the law" and "in compliance with all regulations".
Anderson said the allegations relate to business propriety during the pandemic, before McMurdock became an MP last year.
The Sunday Times alleged that McMurdock borrowed tens of thousands of pounds under the government's Bounce Back loans scheme, which was designed to help struggling businesses during the Covid-19 pandemic.
The newspaper said the loans were worth a total of £70,000 and were applied for through two companies - JAM Financial Limited and Gym Live Health and Fitness Limited.
JAM Financial Limited is alleged to have taken out the maximum loan of £50,000, a level of loan that required a turnover of at least £200,000.
Gym Live Health and Fitness Limited is alleged to have taken out loans worth £20,000, which would have required a turnover of £100,000.
The newspaper claimed that JAM Financial Limited had no employees and negligible assets until the pandemic, and that Gym Live Health and Fitness Limited was dormant until January 31, 2020.
BBC News understands Reform's internal investigation is likely to be led by someone from outside the party and will take at least a few weeks.
In statement, McMurdock said his business dealings had been assessed by "appropriately qualified professionals" and "absolute compliance was confirmed".
He continued: "As a precautionary measure, and for the protection of ReformUK, I have asked to have the whip suspended temporarily."
McMurdock won his seat last July by just 98 votes, beating Labour into second place and taking the seat from the Conservatives.
A since-deleted profile published on Reform's website quoted McMurdock as saying he worked in business prior to standing for the party, including at the banks Goldman Sachs and Lehman Brothers.
He is the second of the five Reform MPs elected in 2024 who have since lost the party whip, after Rupert Lowe was suspended in March.
That came after the party alleged the Great Yarmouth MP had made "threats of physical violence" against then-chairman Zia Yusuf.
The Crown Prosecution Service later said Lowe would not face criminal charges over the claims, which he called "false" and a "brutal smear campaign". He now sits in the Commons as an independent.
Reform's Sarah Ponchin won the Runcorn by-election in May, taking the party's Commons cohort back to five.
However, McMurdock quitting the party whip means Reform now has four sitting MPs.