A couple who say they were accused of tax fraud after relying on advice from PricewaterhouseCoopers are suing the firm for more than £2m.

John and Marion Coll claim PwC was negligent and cost them £1.5m in tax penalties and interest as a result of incorrect tax returns.

The dispute centres around advice they received after selling their shares in Grosvenor Nursing Agency to Nestor Healthcare in 1997 for £2.5m in loan notes. The couple moved to Belgium, where they lived for two years while the loan notes were redeemed, to save capital gains tax, on advice from PwC, according to a High Court writ.

PwC then drafted self-assessment tax returns and gave tax advice which was fundamentally mistaken, on the basis that their application for capital gains tax clearance was accepted by HMRC when it had been refused, the writ also says.

PwC said in a statement: "Whilst it is not appropriate to comment on client matters we are aware of the proceedings and they are currently stayed."