Barlow Lyde & Gilbert, Hill Dickinson and Gateley could be held liable for £500,000 in client money shortfalls relating to the Halliwells collapse, according to a letter sent out by the Solicitors Regulation Authority (SRA) last month.

The SRA wrote to the three firms on 21 April warning them to pay the money or face investigation. The shortfall includes £305,000 in unpaid client money with an additional £272,000 in interest added to the base amount.

The letter was sent by the SRA's legal adviser Bevan Brittan to CMS Cameron McKenna, which advises Halliwells administrator BDO.

Gateley Manchester head Rod Waldie said: "The letter issued by the SRA is a statement of the regulatory responsibilities that our members are very mindful of. It sets out the SRA's position in regards to Rules 19 and 24, which relate to professional disbursement and client interest.

"The figures stated in the SRA's letter are notional and refer to a 'theoretical' loss should the three purchasing firms – i.e. Gateley, BLG and Hill Dickinson – not meet these responsibilities.

"Gateley has been fully committed to ensuring that none of its clients have lost out and we are extremely respectful of our obligations in respect of solicitors' accounts rules. This whole matter is part of ongoing contractual discussions between the purchasers and the administrator, BDO, which relates to monies due to the purchasing firms. This discussion is entirely separate from the clients' position."

The letter is the latest development in the ongoing saga following the collapse of Halliwells last summer, and comes after news emerged in February of tensions among former Halliwells partners over a decision to limit the number of ex-partners eligible to seek a tax rebate from HM Revenue & Customs.

According to a report issued by BDO in the same month, the defunct law firm owes unsecured creditors more than £190m.

In a statement, the SRA said: "The SRA is continuing to deal with ongoing issues arising from the administration of Halliwells to ensure that the public interest is protected."

For the full story of the break-up of Halliwells, see Divided we fall – behind the headlines, the drama and confusion of Halliwells' collapse.