A Suffolk accountancy firm is under investigation by a specialist police unit amid fraud allegations after its former clients were instructed to repay their tax refunds.

Apostle Accounting, based in Marriotts Walk in Stowmarket, is being probed by the Eastern Region Special Operations Unit (ERSOU), which is funded by the seven police forces across the East of England.

It comes after the company's ex-clients came forward to reveal they had been ordered to repay tax rebates received through the firm to HM Revenue & Customs (HMRC).

Apostle has repeatedly denied any wrongdoing – blaming HMRC for the issue – and has said it would co-operate with any investigation.

An ERSOU spokesman said: "Officers from the Eastern Region Special Operations Unit are investigating after being made aware of allegations of fraud involving a business in Stowmarket, Suffolk.

"Investigators are liaising partner agencies, and enquiries are ongoing to establish if any offences have been committed."

A spokesman for Apostle added: "We support and will co-operate with any investigations that contribute towards achieving a positive outcome for our former clients.

"As of now, we have not been contacted by the police or any other authorities regarding any formal investigations."

The issue came to light in mid-April as several of Apostle's former clients received letters from HMRC to repay their tax rebates they received years earlier.

The clients previously used Apostle to claim a tax refund – some to the tune of thousands of pounds, with the firm taking a 20% cut – only for HMRC to reclaim the money later on, saying they were not entitled to it.

Suffolk police later revealed an investigation had been launched into the matter, but was unable to specify any further details.

East Anglian Daily Times: Dr Dan Poulter, Central Suffolk and North Ipswich MPDr Dan Poulter, Central Suffolk and North Ipswich MP (Image: Archant)

Dr Dan Poulter, MP for Central Suffolk and North Ipswich, recently confirmed that HMRC would not be pursuing prosecutions or imposing fines on former Apostle clients that have been left with unexpected tax bills.

He said the clients have been "caught up in this affair through no fault of their own".