On his return to the UK after more than four years in a Singapore jail he said: "I want to state clearly here that I know I did wrong."

The BBC's Alva McNicol reports on the rogue trader's return

"I am not proud of my activities as a trader with Barings Bank in Singapore. I was foolish and very much regret what happened."

A tired-looking Leeson, 32, added: "I've done my time and I want to get on with the job of rebuilding my life."

Leeson said his time in Tanah Merah prison in Singapore had been far from easy. "The regime was tough, but I must add that it was ultimately fair too."

An emotional day

He arrived with his lawyer Stephen Pollard on a British Airways flight at 0543 BST, and read from a prepared statement, refusing to answer journalists' questions.

"As you can perhaps imagine, this is a very emotional day for me," he said. "I've been in prison in a foreign land for four years and four months.

"Just to be home and to see my family is something I have longed for all that time.

"Also, I have really looked forward to doing the ordinary things, like being able to have a cup of tea or a drink with my mates, when I want to, where I want to.

"Simple things like these have come to mean a lot to me over the last four years."

Suffering from cancer

Leeson was released from the maximum-security Tanah Merah jail on Saturday.

During his time in prison he was diagnosed as suffering from colon cancer. An operation last August to remove a tumour and parts of his colon and large intestine succeeded, but he still has a 30% chance of the cancer recurring within five years.

Leeson's statement: Short and to the point

He told the Heathrow news conference that he was planning to continue receiving treatment after being referred to a British cancer specialist by doctors in Singapore.

Leeson will have to rebuild his life on his own. His wife Lisa, who initially stood by him, has left him and since remarried.

He said he was told on entering prison that he was about to find out who his true friends were. "Nothing could be more true. I have found out who my friends are, and I would like to thank all of them for their support.

"But above all, I would like to thank my family, without whose constant love and support, I might not have got through it."

No hidden funds

Leeson was arrested in Frankfurt after going on the run

Leeson is reported to have sold the exclusive story of his downfall and the collapse of Barings Bank to the Daily Mail for £100,000.

His lawyer, Mr Pollard, denied speculation that Leeson, a plasterer's son from Watford in Hertfordshire, had secretly hidden £2m from his illegal dealings. "That is complete and utter nonsense," he said.

Leeson would have £5,000 a month to spend on medical and living expenses following a High Court order freezing his assets, said Mr Pollard.

He is not allowed to spend any money without giving two days written notice to liquidators investigating the collapse of the bank.

The judgment specifically prevents him from cashing in on his autobiography, Rogue Trader, or the film adaptation starring Ewan McGregor that was launched last week. It also prevents him receiving cash by selling his story to the media.

Huge losses

Pollard: "Suggestion he has a £2m stash is utter nonsense"

Leeson's unauthorised deals brought down Barings as he tried to cover losses, mainly incurred by trading in volatile Japanese futures, in Singapore's financial markets.

In February 1995, Barings' bosses uncovered losses totalling £850m. After going on the run, Leeson was arrested in Frankfurt and later extradited to Singapore, where he was jailed for six and a half years. He has been released early for good behaviour.

Mr Pollard said that he did not believe there would be any criminal action against Barings officials now that Leeson was free to tell his whole story.

"To his credit, from day one, Nick has said he was the only person who was involved in criminal action."

However, Mr Pollard said that Leeson feels he is the only one in the bank who has really paid a serious price for its collapse.