Protests by anti-agreement unionists and the victims group, Families Acting for Innocent Relatives, marked the meetings at Stormont held between Mr Tony Blair and the Taoiseach, the political parties and representatives of nationalist residents' groups.
As he arrived and left Parliament Buildings, Mr Blair was the focus of noisy challenge. Mr Cedric Wilson of the Northern Ireland Unionist Party called to him from the balcony as he climbed the steps with Mr Ahern.
"Are you prepared to support the democrats? That is the challenge facing you today," shouted Mr Wilson as Mr Blair entered the building.
On his departure he was surrounded by protesters from FAIR, who represent the families of those killed and injured by republican paramilitaries.
The protesters waved banners and followed Mr Blair to his helicopter, taunting him. They chanted that terrorists must be kept out of government.
At lunchtime there was chaos in the Stormont grounds as republicans staged a protest at Lord Carson's statue.
Two protesters, one carrying a Tricolour, climbed on top of the plinth and traded insults with members of the Democratic Unionist Party.
A DUP Assemblyman blocked the car of the nationalist residents' group spokesmen, Mr Breandan Mac Cionnaith and Mr Gerard Rice, as they arrived at Stormont for their meeting with Mr Blair and Mr Ahern. But they were eventually allowed to pass through the DUP roadblock as police officers continued to negotiate with the republicans sitting at Carson's feet.
The Rev Ian Paisley and senior members of his party protested to police officers that the two republicans had been allowed to climb on to the statue.
"We are going to get them down off that statue and down they will go," Dr Paisley said.
The DUP Assembly member for South Down, Mr Jim Wells, described the protest as "a calculated insult to the unionist people".
Following negotiations with the RUC and Sinn Fein Assembly members, including Mr John Kelly, a ladder was hoisted against the statue and the two protesters climbed down and were taken away by police.