ALEXANDRIA, Virginia (Reuters) - A US client of London-based HSBC pleaded guilty to conspiracy in connection with assets stashed abroad to evade taxes, part of a widening crackdown on foreign banks and their customers.

The plea is the first among the US government's recent tax prosecutions that involves a major bank other than Swiss banking giant UBS AG. UBS last year admitted that it actively helped US clients to hide money abroad.

HSBC was not named in the court documents, which referred to "one of the largest international banks in the world" ... "headquartered in England". But a person familiar with the matter identified the bank as HSBC.

Andrew Silva, of Sterling, Virginia, a doctor, pleaded guilty in US District Court for the Eastern District of Virginia to conspiracy to defraud the US government by hiding about $250,000 in an account at a Swiss unit of HSBC.

Dressed in a black suit and accompanied by a weeping woman, Silva also pleaded guilty to lying to US customs authorities, who questioned him as he traveled into the United States with some of the money.

US District Judge Liam O'Grady set May 7 for a sentencing hearing. Silva faces a maximum sentence of ten years in prison and a maximum fine of $500,000.

The court filings listed the defendant's banker as an unindicted co-conspirator. HSBC declined to comment.

Silva was notified in August of 2009 that the bank would stop holding his account. He then attempted to send the money back through the mail in increments of less than $10,000 to evade reporting rules, according to the court documents.

It was in August of last year that the United States, the Swiss and UBS agreed to end a civil dispute over thousands of UBS accounts the US government is still seeking.

UBS and its US clients have been the target of the US government's stepped-up effort to catch tax cheats using offshore accounts.

UBS settled criminal and civil charges against it last year, paying $780 million and agreeing to disclose about 4,450 client names, although that deal is now muddled because of a recent Swiss court ruling in favor of a UBS client.

US authorities also gained nearly 15,000 new account names in a voluntary amnesty programme last year and have said they will use the information gleaned to go after other individuals and financial institutions.

When asked whether Silva's bank could be the next targeted after UBS, a government attorney declined to directly answer. However, he pointed to the help Silva got from the Zurich-based banker, the unindicted co-conspirator.

"We're definitely not going to tolerate that type of behaviour," Justice Department attorney Kevin Downing said. "We follow the evidence."

Court documents said a Zurich attorney and the Swiss banker warned Silva he could not use wire transfers to get his money out of Switzerland, for fear of leaving a paper trail. He was to deal only in cash and was given individually wrapped "bricks" to send the money back in chunks of $100 bills.

When asked if he was going to file corrected tax returns for 2003 to 2008, Silva told the court: "I really want to correct the things that I've done wrong."

While it is not illegal to keep money overseas, accounts with an aggregate value of more than $10,000 must be declared to the US Treasury.

Additionally, the movement of over $10,000 into or out the United States must also be reported to US authorities. Structured mailings of less than $10,000 to evade this requirement are prohibited.