A loyalist mob threw fireworks and stones at a community centre in east Belfast where the former IRA bomber who tried to assassinate Mrs Thatcher was speaking at a cross-community event.
Around 60 people gathered outside the Skainos centre on the Newtownards Road last night waiting for Patrick Magee, the man behind the bombing of Brighton's Grand Hotel during the Tory Park Conference in 1984.
The blast killed five people and injured 34. Among the injured were Lord Tebbit and his wife.
The prime minister at the time, Margaret Thatcher, had a narrow escape.
In recent years, Mr Magee has been associated with projects that work with groups specialising in conflict resolution, reconciliation and victim support.
As he arrived the crowd hurled abuse and threw missiles at him before he was bundled in through a back door.
A heavy police presence held the crowd back before more reinforcements arrived on the scene.
The windows of two police vehicles were smashed during the violence and four officers sustained minor injuries.
At one stage a recycling bin was set alight by the mob and pushed into the middle of the Newtownards Road, blocking traffic.
At the height of the disorder around 250 people were outside the centre waiting for Mr Magee to leave the building
The event, entitled Listening To Your Enemies, was part of Four Corners Belfast, a cross-community religious festival.
Jo Berry who lost her father, Sir Anthony Berry in the Brighton bomb and has since forgiven Mr Magee for the attack, was also speaking at the event.
Prior to the event, anti-republican graffiti was painted on the Skainos building which belongs to the East Belfast Methodist mission.
Earlier Mission spokesman Rev Gary Mason (below) said he was determined the event would go ahead despite the hostility.
"The whole idea of the event is looking at peace and reconciliation, and the only way you bring conflict to an end is through negotiation," he told the Belfast Telegraph. "Graffiti isn't going to bring it to an end, it's not going to deal with your enemies, it is simply going to isolate them and create even more division.
"We have video evidence as well because this is a new site so there are a number of security cameras so the folk that did that are on camera," he added.
East Belfast community worker Jim Wilson said people were entitled to their views, but they should be expressed peacefully.
"They should do it in a proper manner if they have disagreements with the church or with anyone within loyalism," he said.
Police are treating the Skainos graffiti incident as a hate crime and have begun an inquiry into last night's disorder.