Reports of possible furlough fraud have topped 26,000.
HM Revenue & Customs (HMRC) said it had received 26,232 reports by the beginning of last week, up from 23,500 at the start of last month and double the 13,114 in October, reports The Sunday Times.
A total of 11.4 million jobs have been protected by the scheme.
Furlough has cost taxpayers £57bn. Users have come under pressure to return furlough funds when they are back in profit, especially if they want to pay dividends.
Firms have so far returned £700m. As well as furlough, there have been reports of fraud on other schemes.
The cabinet office said banks had filed 24,000 suspicious activity reports (SARs) to the police about the £46bn Bounce Back Loans scheme, and 15,983 SARs about other potential misuses of covid schemes.
The cabinet office’s fraud line, launched in October with Crimestoppers, has also received 1,800 reports.
HMRC said fraudulent claims were “unacceptable” and urged people to report any suspicious claims.