UPDATE 1-Legal claims over RBS cash call near 4 bln pounds

(Adds details of RBoS Action Group claims)

By Kirstin Ridley and Steve Slater

LONDON, May 16 (Reuters) - Hundreds more investors havejoined an unprecedented group legal action against Royal Bank ofScotland, alleging they were misled during an emergencycash call in 2008, and are claiming damages of around 4 billionpounds ($6.7 billion).

RBoS Action Group, which represents the largest group ofshareholders, said it had filed claims by Friday and would lodgemore next week. The claims could be for at least 1.2 billionpounds.

That adds to claims from three other groups that total morethan 2.5 billion pounds on behalf of big financial institutionsand thousands of small investors in the first American-styleclass action set to hit English courts.

Thursday marked the six-year anniversary of when the sharesRBS sold in its emergency rights issue began trading and couldbe the cut-off point under English law after which damagesclaims are no longer be accepted.

Fred Goodwin, the former boss of the now state-backed RBS,asked shareholders to stump up 12 billion pounds at the heightof the credit crisis to shore up the bank's capital position,which fell dangerously low after it paid top dollar for parts ofDutch peer ABN Amro and lost billions on U.S. credit marketassets.

Under Goodwin, dubbed "Fred the Shred", RBS staged ameteoric rise to global prominence, expanding so aggressivelyinto wholesale banking that its near-failure at the height ofthe credit crisis threatened to fell the UK financial system.Shareholders lost around 80 percent of their investments.

"This is a novel and unique case - there has never beenanything quite like it in the English courts before," said CliveZietman, a partner at law firm Stewarts Law, which isrepresenting 313 UK and international institutional clientsincluding local authorities, pension funds and asset managers.

Goodwin, alongside former chairman Tom McKillop and twoother former executives, is likely to be called as a key witnessif the case goes to trial - although sources said that may nothappen until early 2016.

RBS rejects allegations its former directors misledinvestors or acted illegally.

"These things will be set out in court rather than in anearly settlement, we have a good defence on this," RBS ChiefExecutive Ross McEwan said this month.

NEW HELM

RBS is now being run by a new team and is 80 percent ownedby the government, which was forced to step in with a 45 billionpound taxpayer-funded bailout.

Investors claim RBS failed to disclose how bad its capitalposition was, that its risk management and controls were"fundamentally flawed" and that the integration of ABN Amrobusiness was not going well.

Investors represented by Stewarts Law are claiming more than1.3 billion pounds, while law firm Quinn Emanuel has filedclaims on behalf of five of the biggest institutions - includingtop 10 investors at the time Legal & General, StandardLife and Prudential - which are likely to totalabout 1.2 billion pounds.

The main uncertainty about the size of claims RBS faces isfrom the RBoS Action Group. The group said it has signed upabout 13,500 retail investors and about 100 institutions, andhas had a surge in claims in recent weeks as the six-yeardeadline has approached.

It had filed claims by Friday on behalf of investors whobought 695 million shares in the rights issue, a spokesman forthe group said. How claims are calculated is complex, but thatwould indicate claims of about 1.2 billion pounds.

The group will submit more claims next week so the numberwill rise, the spokesman said, but he declined to estimate byhow much. Almost all of the claims so far were on behalf ofinstitutions, he said.

A fourth group represented by law firm Leon Kaye represents4,200 retail investors with claims worth 22 million pounds.

A London court hearing around early July will set out theroadmap for the rest of the case, including timing of a trial. ($1 = 0.5954 British Pounds) (Editing by Erica Billingham)