Britain has refused to make any concessions to the Government over plans to hold an inquiry in private into the killing of Belfast solicitor Pat Finucane.
Serious divisions emerged yesterday at a meeting in London between officials from the Northern Ireland Office, the Department of Foreign Affairs and the Department of the Taoiseach.
The meeting was described by the Department of Foreign Affairs last night as "full and frank", a diplomatic code used when a serious disagreement exists.
The legislation would give ministers the power to order an inquiry to hear evidence in private, and to bar the production of some evidence altogether to protect British national security.
The Irish officials sought concessions on the shape of the Inquiries Bill, which has already been passed by the Lords and will go before the House of Commons next Tuesday.
In particular, the Government wants an inquiry into the 1989 killing of Mr Finucane by the UDA to be held under the 1921 Tribunals of Inquiry Act, which would allow for hearings in public.
Failing that, the Government wanted a change to Clause 20 of the Inquiries Bill so that British ministers would not restrict such an investigation.
The lack of British concessions means that the Finucane inquiry will feature prominently during the Taoiseach's visit to the United States next week.
A spokeswoman said last night that Mr Ahern intends to raise the British stand during his meeting with President George Bush in the White House.
"He is adamant about our position on this. And it hasn't changed. He has mentioned it at every meeting he has had with Tony Blair," the spokeswoman went on.
Earlier this week Mr Ahern described the British government's position as "unsatisfactory" and "not in line or in tandem" with the recommendations made by Canadian judge Peter Cory.
The Taoiseach said then he hoped that yesterday's meeting of officials would have provided the means to "see if we can get an agreed basis".
Judge Cory investigated the most controversial killings of the Troubles, including Mr Finucane's, Robert Hamill in Portadown in 1997, LVF leader Billy Wright in the Maze Prison in 1997 and Rosemary Nelson in Lurgan in 1999.
He may attend a Capitol Hill hearing in Washington into the Finucane killing, which has been organised by Republican congressman Chris Smith.
Mr Finucane's widow, Geraldine, will speak at the hearing, along with Jean Winter of British Irish Human Rights Watch, and Mr Bush's special envoy to Northern Ireland, Dr Mitchell Reiss.
The proposed British legislation has already been sharply criticised by Lord Saville of Newdigate, who chaired the Bloody Sunday inquiry.
Last week he said: "I would not be prepared to be a member of an inquiry if at my back was a minister with power to exclude the public or evidence from the hearings."
The judge, whose concerns are shared by the Lord Chief Justice, Lord Woolf, and other British legal figures, said: "I take the view that this provision makes a serious inroad into the independence of any inquiry.
"It is likely to damage or destroy public confidence in the inquiry and its findings, especially in any case where the conduct of the authorities may be in question."
The inquiry should itself have the power to decide what evidence was heard in public and what documents were published.
"The idea that this would not be done by the inquiry but by the government, which might have a vested interest in the findings, strikes me as unacceptable."