The Government has insisted plans to unveil proposals for a new power-sharing executive later this week will go ahead despite the killing of Denis Donaldson.
"The dark detail that surrounds this murder is a tragic and regrettable reminder of Northern Ireland's past," a Government spokesman said.
"The focus has to be on allowing positive politics to take root and achieve agreement with leadership in Northern Ireland."
Mr Blair and Mr Ahern are due in Armagh on Thursday to announce the proposals were they are expected to announce a time-table to revive shadow power-sharing in Northern Ireland.