Fred Cobain has threatened to boycott graduation

But Mr Cobain, an Ulster Unionist, said the decision to invite Mr Byrne was "the height of stupidity".

He said the formal duties should be left to Mr Cramphorn.

"Pat Byrne is a member of the Garda Siochana, he's nothing to do with the police service and should not be officiating.

"That's my position and I think I'm speaking for all the members of the unionist family on the police board.

"We will not attend if Pat Byrne is officiating and I don't see any reason for him to do that."

Board member Eddie McGrady, of the nationalist SDLP, said co-operation between the gardai and the new police service was "essential for effective policing".

Eddie McGrady: "Nothing wrong" with inviting commissioner

"The police service and the garda need to have, and do have, a very close partnership," he said.

"They've got to have it, if we're to resolve the crimes of terrorism, of the drug barons. It is shown so clearly that that partnership must be very close, in terms of the Omagh bombing investigation.

"There's nothing wrong with the attendance of a garda commissioner."

Focus

Pauline McCabe who is an independent member of the Policing Board, said the controversy was "just another distraction".

She said it was "first and foremost a day that should be for the students and their families."

"They should be the focus of attention that day and nothing else," she added.

It is expected that talks will continue behind the scenes to try to resolve the political dispute.

The arrangements for next week's ceremony have yet to be finalised.

The first 40 recruits to the Police Service of Northern Ireland to graduate next week, are the first trained specifically for the new police service.

It follows the sweeping changes to policing in Northern Ireland under which the Royal Ulster Constabulary was changed to the PSNI last November.

The first wave of new officers were recruited on a 50% Catholic, 50% Protestant and others basis.

The changes followed a report from Chris Patten's policing commission which made more than 175 recommendations.

The commission was set up under the Good Friday Agreement.