Paul Wolfowitz was under pressure to resign as president of the World Bank yesterday after admitting he was personally involved in securing a large pay rise and promotion for a Bank official with whom he was romantically involved.

The Bank president issued a public apology, saying: "I made a mistake for which I am sorry".

The apology came after the Financial Times revealed that Mr Wolfowitz ordered the World Bank's head of human resources to offer Shaha Riza the pay rise and promotion as part of a secondment package to the US state department.

The instructions were set out in a memorandum dated August 11 2005, according to two sources who have seen the document.

The Bank's board of directors, who represent its shareholder governments, met in emergency session yesterday to review the findings of their own investigation into the Riza assignment.

Pressed by journalists at the press conference of the Bank's spring meeting as to whether he would resign over his handling of the Riza case, Mr Wolfowitz said he would "accept any remedies" the board proposes.

He did not comment on the specifics of the memo.

Moments later, in the lobby of the Bank's headquarters in Washington, the Bank president made an impromptu address to staff who had gathered to call for his resignation.

An emotional Mr Wolfowitz told staff the controversy had been "very painful" and apologised to them in person for his handling of the affair.

Alison Cave, the chair of the staff association, welcomed the apology but said Mr Wolfowitz must "act honourably and resign".

Mr Wolfowitz said he acted as he did to shield the Bank from a lawsuit if Ms Riza was forced to leave because of staff rules that prohibit its employees from working for anyone with whom they are romantically involved.

He denied charges of a cover-up, declaring: "I did not attempt to hide my actions nor make anyone else responsible."

The Bank president made a plea for "understanding" saying he faced a "painful personal dilemma" at a time when he was new to the Bank.

Ms Cave said Mr Wolfowitz had "broken the staff's trust on this and many other issues" and if the board failed to ask him to step down, the staff association would call a vote of no confidence in him.

The US administration, meanwhile, offered less-than-full-throated backing for Mr Wolfowitz. Tim Adams, the under-secretary for international affairs at the US Treasury, said that a process was in place to examine the issue at the board level.

Asked if the US still supported Mr Wolfowitz as Bank president, Mr Adams declined to answer, referring back to his earlier remarks about respecting the board process.

In the August 11 2005 memorandum, two sources told the Financial Times, Mr Wolfowitz directed Xavier Coll, the Bank's vice-president for human resources, to offer Ms Riza specific terms as part of a secondment package.

These included a promotion, a pay rise above that normally associated with the promotion, and arrangements to ensure Ms Riza received exceptional annual pay increases. Only the promotion had been recommended by the board's ethics committee, two sources told the FT. The terms and conditions were not approved by the committee or its senior legal officer, then general counsel Roberto Danino.

Mr Wolfowitz went to the board on Thursday morning and proposed that it should "establish some mechanism to judge whether the agreement reached was a reasonable outcome."