RBS has to be rescued by the government in November
Two local authority pension funds have told the BBC they are suing Royal Bank of Scotland (RBS) for compensation.
The Merseyside and North Yorkshire funds accuse RBS of withholding the extent of the bank's problems before its government rescue last year.
They will be represented by Cherie Booth QC, wife of Tony Blair.
The legal action against RBS, which has declined to comment, has been launched in the US. Other UK pension funds are said to be considering joining them.
Stephen Everard, managing director of class actions specialists Goal Group, thinks they should.
"Local authorities not participating in US class actions such as the RBS case risk losing out on a massive opportunity to seek compensation and plug their escalating pension gap," he said.
But others are less sure.
"RBS is likely to object to English or European investors being included as claimants in a US class action, on the basis that the US courts do not have jurisdiction to hear those disputes," predicted Guy Pendell, litigation partner at city law firm CMS Cameron McKenna.
RBS gained an extra £12bn from shareholders following the conclusion of a successful share issue in June of last year.
Yet just five months later in November, the bank needed to accept a £20bn rescue package from the government in exchange for a 58% stake in the bank, which was subsequently increased to 68%.
The then RBS bosses, led by Sir Fred Goodwin, have subsequently stood down from the bank.
At the same time, the firm's share price has collapsed, down from 243 pence immediately after the June share issue to the current 22.5p.
Peter Murphy, a partner at Sackers, a specialist pension law firm, said that the US legal system was better suited to this type of claim.
"US lawyers act on a 'no win, no fee' basis and plaintiffs do not have to pay for the other side's legal costs even if they lose," he said.
However, he expressed surprise that Ms Booth was involved in the case.
"Her profile is mainly in UK and European human rights law, not US securities litigation. But that is not to say she doesn't have relevant expertise," he said.
"Her involvement in the case will certainly add greater public interest to an already high-profile media event."
Moreover, added Mr Pendell: "UK shareholders may seek to pursue these claims in the US because it is perceived to be a more claimant-friendly forum., but that does not necessarily mean that the US should or will assume jurisdiction of the claim."
Peter Wallach, the head of the Merseyside Pension Fund, said he wished to ascertain whether statements made by the former RBS bosses before the share issue and subsequent government rescue "were in any way inaccurate or misleading to shareholders".
"The purpose of the litigation from the side of Merseyside Pension Fund is to hold management to account," he said.
"Our concern is that perhaps management didn't indicate to shareholders the full extent of the deterioration in the bank's finances when it first came to shareholders for additional capital."
The legal action has come in the shape of a US class action civil lawsuit, which enables a number of complainants to join together and make one, collective claim.
Mr Wallach added that the case was being taken on a no-win, no-fee basis, so there was no risk to its pension holders.
The North Yorkshire Pension Fund website says it covers employees of the county council, district councils within the region, police, fire service, universities and colleges, national parks and Yorkshire Tourist Board, among others.