The Queen inadvertently walked into the latest row sparked by remarks from Mrs McAleese, who was forced to cancel a trip to Belfast four years ago even though she apologised for suggesting children in the province had been taught to hate Catholics in the same way Nazis learned to despise Jews.

Though the two heads of state appear to have made significant progress towards a Dublin visit - which would be the first by a reigning British monarch since partition in 1921 - Mrs McAleese said yesterday it could not happen until devolution is complete.

And she made clear that she meant when the devolution of policing and justice responsibilities takes place.

"I think the day is significantly closer," said Mrs McAleese after meeting the Queen.

"We know that it is dependent on the completion of devolution, which hopefully will not be too far away. That means the return of policing and criminal justice responsibility to the Executive in Northern Ireland.

"We had hoped that would be May. Now we are not entirely sure what the time scale is. We hope it will keep closely to the timetable. When that is done, when devolution is completed, I think then anything is possible."

Mrs McAleese said she thought it unlikely that a visit would take place this year, but she hoped one could take place "sooner rather than later."

Outraged unionists last night slammed the President's statement and warned it would prove counterproductive for the policing and justice hand-over.

Ulster Unionist leader Sir Reg Empey said he was angered by the statement which he said would be interpreted as pressuring unionists over policing and justice, which had been the "most sensitive issue" over the past 30 years.

And the DUP's Stephen Moutray said it seemed almost every statement by Mrs McAleese actively sought "to antagonise the unionist population."

On the issue of the Queen visiting Dublin, however, Mrs McAleese three years ago revealed the British and Irish Governments were agreed it should take place and that the timing would be for them to decide.

But speaking after a Cooperation North venture in London with the Queen, she also said it would be depended on the "successful development" of the political process in Northern Ireland "over time."

Mrs McAleese, who is expected to be present again today at the first Royal Maundy Thursday money to be distributed in Northern Ireland, is known to be in regular contact with UDA chief Jackie McDonald, who has played golf with her husband, and to have supported several loyalist projects.

But Mr Empey last night argued: "I cannot fathom what this is designed to achieve and why there is all this pressure over this issue, which is even being linked into the economic conference in May. It is only likely to prove counter-productive."

There was no immediate SDLP reaction but Sinn Fein Deputy First Minister Martin McGuinness warned: "...if we can't reach agreement, we are going to be in big trouble."