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* Media reports say HSBC helped wealthy dodge taxes
* List of rock stars, Hollywood actors, royalty
* U.S. could revisit 2012 agreement -law enforcementofficial
* Shares down 2 percent (Releads with comments from source on U.S. investigation)
By Steve Slater, Joshua Franklin and Aruna Viswanatha
LONDON/ZURICH/WASHINGTON, Feb 10 (Reuters) - HSBC HoldingsPlc faces investigation by U.S. authorities and aninquiry by British lawmakers after admitting failings by itsSwiss private bank that may have allowed some customers to dodgetaxes.
U.S. prosecutors have stepped up efforts to establishwhether HSBC, the world's second largest bank, helped Americansevade taxes after media reports said the bank had helped wealthycustomers conceal millions of dollars of assets.
U.S. authorities are also probing whether HSBC manipulatedcurrency rates, and a U.S. law enforcement official said onMonday the investigations could prompt the Department of Justiceto revisit a 2012 deferred prosecution agreement with the bank.
The agreement was part of a $1.9 billion settlement thatallowed HSBC to avoid criminal charges after it was found tohave helped move hundreds of millions of dollars in illicit drugmoney through the U.S. financial system.
"It is quite possible that the (agreement) may be reopenedas a result of the bank's activities on either or both the taxevasion and foreign exchange manipulation front," said the U.S.law enforcement official, who requested anonymity because theinvestigations are ongoing.
British lawmakers said they plan to open an inquiry into thebank after it came under fire for its past practices inSwitzerland.
HSBC shares fell 2 percent by 0845 GMT on Tuesday,underperforming the European bank index. They fell 1.6percent on Monday after media reports about the activities ofits Swiss operation based on client data from 2006-07.
A spokesman for HSBC declined further comment on Tuesdayafter the bank issued a statement late on Sunday in response tothe media reports.
SWISS ACCOUNTS
The International Consortium of Investigative Journalists(ICIJ), which coordinated the release of details of leakedclient data, said a list of people who held HSBC accounts inSwitzerland included soccer and tennis players, rock stars andHollywood actors.
Reuters could not independently verify any of the nameslisted by the ICIJ. Having a Swiss bank account is not illegaland many are held for legitimate purposes.
The newly released HSBC Swiss client list included royaltysuch as Morocco's King Mohammed, politicians, corporateexecutives including former Santander chairman EmilioBotin, who died last year, and wealthy families, the ICIJ said.A spokesman for the Moroccan royal palace declined to comment.
Uruguayan soccer player Diego Forlan, who was also on thelist, on Monday denied evading taxes by hiding money in Swissaccounts with HSBC.
The documents also listed arms dealers, people linked toformer dictators and traffickers in blood diamonds, and severalindividuals on the current U.S. sanctions list, includingGennady Timchenko, an associate of Russian President VladimirPutin. Timchenko's Volga Group declined to comment.
"We acknowledge and are accountable for past compliance andcontrol failures," HSBC said after news outlets published theallegations about its Swiss private bank.
The Guardian and other media cited documents obtained by theICIJ via French newspaper Le Monde.
HSBC said that its Swiss arm had not been fully integratedinto HSBC after its purchase in 1999, allowing "significantlylower" standards of compliance and due diligence to persist.
CURRENCY BRICKS
The Guardian asserted that the files showed HSBC's Swissbank routinely allowed clients to withdraw "bricks" of cash,often in foreign currencies which were of little use inSwitzerland.
HSBC also marketed schemes which were likely to enablewealthy clients to avoid European taxes and colluded with someto conceal undeclared accounts from domestic tax authorities,the Guardian said.
The reports began a political debate in Britain ahead of aparliamentary election in May, with Margaret Hodge, a senioropposition Labour Party lawmaker, saying tax authorities haddone too little to collect tax money.
HSBC's admission of failing has renewed scrutiny on StephenGreen, who was executive chairman between 2006 and 2010. Greenwas later made a member of Britain's upper house of parliamentand served as minister for trade and investment between 2011 and2013.
The HSBC client data were supplied by Herve Falciani, aformer IT employee of HSBC's Swiss private bank, HSBC said. HSBCsaid Falciani downloaded details of accounts and clients at theend of 2006 and early 2007. French authoritieshave obtained data on thousands of the customers and shared themwith tax authorities elsewhere, including Argentina.
Switzerland has charged Falciani with industrial espionageand breaching the country's secrecy laws. Falciani could not bereached for comment but has previously told Reuters he is awhistleblower trying to help governments track down citizens whoused Swiss accounts to evade tax.
HSBC said it was cooperating with authorities investigatingtax matters. Authorities in France, Belgium and Argentina havesaid they are investigating.
HSBC said the Swiss private banking industry, long known forits secrecy, operated differently in the past and this may haveresulted in HSBC having had "a number of clients that may nothave been fully compliant with their applicable taxobligations."
Its private bank, especially its Swiss arm, had undergone "aradical transformation" in recent years, it said in a detailedfour-page statement.
(Additional reporting by Tom Miles in Geneva, Mark John inParis and Andrew Osborn in London; Editing by Alexander Smith,Keith Weir, Jane Merriman, Grant McCool)
