The FBI is stepping up its hunt for America's second most wanted man, who is believed to be in hiding somewhere in the British Isles.

On Monday New Scotland Yard issued an appeal for James 'Whitey' Bulger, a former Boston gang leader who has a $1m bounty on his head.

Bulger's description

Around 5' 8" tall Weighs around 11 stone White hair, blue eyes Pronounced Boston accent Animal lover Known to frequent libraries and historic sites Suffers from angina and takes Atenolol medication

Bulger, who is on the FBI's list of Ten Most Wanted People, is suspected of 19 murders, drug trafficking, extortion and money laundering.

Bulger, 73, escaped arrest in 1995 after being tipped off by an FBI agent, John Connolly Jr, who was on his payroll.

He has been spotted in London on several occasions, the most recent of them in September last year.

Before he fled Boston he salted away millions of dollars in bank accounts and safety deposit boxes, some of which were in Britain.

In October 2002 Scotland Yard obtained a search warrant and searched a safety deposit box at Barclays Bank in Mayfair.

Inside they found an Irish passport in Bulger's name, a quantity of correspondence and American, British and Swiss currency.

In the 1980s Bulger, the head of the so-called Winter Hill Gang, helped smuggle a cache of weapons from the US to the IRA.

Bulger, 73, is thought to be travelling with his lover, Catherine Greig, a dental hygienist who was indicted in her absence in 1997 accused of harbouring a fugitive.

Catherine Greig is believed to be travelling with Bulger

Detective Superintendent Nigel Mawer, who is leading the hunt for Bulger in Britain, said: "We were informed by the FBI that there had been an alleged sighting of Bulger in Piccadilly, on 10 September 2002.

"A British man had claimed he first met 'an American man' in the gym at the Meridian Hotel Piccadilly in 1994 - but had then seen him again in September 2002 walking in Piccadilly but had not spoken to him.

"He told police that he then saw the film Hannibal and saw a picture of the man's face in a scene in a FBI Most Wanted poster - he had then looked up the face on the FBI website and seeing it was Bulger had contacted the FBI in Washington.

"This man then provided the FBI with a description from which a sketch was created. It is now on the FBI's Most Wanted website."

Bulger has a violent temper and is said to carry a knife at all times.

In the 1980s and early 1990s he was a prized informant for the FBI in Boston and gave much information about rival criminals but it has since transpired that his own gang was responsible for a reign of terror.

A mass grave of some of the Winter Hill Gang's victims was found recently just outside Boston.

Kevin Shanley and another FBI agent visited the UK last week. They have now returned to Boston but would follow up any new leads.

Anyone with information on Bulger or Ms Greig should contact New Scotland Yard on 0207 230 3191 or Crimestoppers anonymously on 0800 555 111.