The SFO, which spent five-and-a-half days interviewing Mr Leeson in his Frankfurt jail, is expected to announce formally today it will not be making an extradition application.
Mr Pollard, who said his request for a meeting with the prosecuting authority had been turned down, attacked the SFO: "They say that they believe that he should be tried in Singapore. However, if the Singaporean request fails they will try him anyway. Either the evidence is such that he can be tried here (which it is) or it is not. They cannot have it both ways."
Mr Pollard said he believed the City establishment was happy to see Mr Leeson sent to Singapore, where the full story could not be told because of the limited scope of the charges against him there, and where he would serve a long prison term.
"In that way he will be seen to be heavily punished and to take all the blame and those who might be embarrassed if the full story were to come out could go on presenting it as an unfortunate, one-off accident."
Sources at the SFO said its decision was being taken with "100 per cent independence".
Mr Pollard said his client had given details, as far as he could remember, of his dealings with senior Barings staff during his interviews with the SFO. Mr Leeson has not accused them of criminal wrongdoing, though he attacked senior management for inexperience in the futures and options market in his interview with Sir David Frost on Monday.
Mr Pollard said a trial in Britain, at which his client would plead guilty of charges of false accounting and of obtaining property by deception, might possibly last only a day and a half.
He gave further details of how Mr Leeson's losses on the secret errors account grew to the horrendous levels that eventually brought down the bank.
"He first used the account to protect his subordinates' errors. But in order to conceal them, he sold options on which he got a premium which was equal to the losses," said Mr Pollard. Although the premium was paid up-front, Mr Leeson's problem was that he was left with an increasing position in the market, which deteriorated as the market went against him. Mr Pollard said he would launch an appeal against the Singaporean extradition request if it is approved.