Sinn Fein will hit a "brick wall" if they again request the early release of the killers of Jerry McCabe, Irish Foreign Minister Dermot Ahern has said.
Garda Jerry McCabe was killed in 1996
Earlier this week Gerry Adams briefed IRA prisoners in the Republic of Ireland and told them his party was still looking for their release.
Garda McCabe died in a 1996 robbery in Adare carried out by IRA members.
Mr Ahern also said images of loyalist rioting made potential investors scrap plans to travel to Northern Ireland.
"In some instances I was made aware of the fact that future investment, particularly in the north, had been put on hold or postponed as a direct result of the scenes of violence which were broadcast on American networks," he said.
Mr Ahern was speaking after meeting Secretary of State Peter Hain on Wednesday.
Four men were convicted of Mr McCabe's manslaughter and jailed for 11 to 14 years.
The four men - Kevin Walsh, Pearse McAuley, Jeremiah Sheehy and Michael O'Neill - said they qualified for release under the Good Friday Agreement and the Irish government had an "obligation" to release them.