Sinn Féin President Mr Gerry Adams today blamed the escalating violence on the streets of Belfast on a "crisis within unionism".
Speaking after an hour-long meeting with the British Prime Minister Mr Tony Blair, Mr Adams said the recent violence in east Belfast was rooted in problems within the unionist community. He said the crisis was manifesting itself in sectarian attacks on vulnerable nationalist communities.
The Sinn Féin leader rejected allegations by First Minister, Mr David Trimble, that the IRA was orchestrating the violence. He told waiting reporters outside Downing Street that there was no evidence of IRA involvement.
Mr Adams, who was accompanied by his party colleague Mr Martin McGuinness, said he had had a good meeting with Mr Blair, whom he maintained had consistently "brought a focus" to the peace process.
However, he said the British Government could not absolve itself of the responsibility for managing the process in a more effective manner.
Last night, a police officer was injured and two men were arrested as violence flared again in Belfast.
A group, including 30 masked men, threw petrol bombs at police and set fire to cars on the loyalist Donegall Pass area of south Belfast. At one stage a masked gunman fired shots in the area, a PSNI spokesman said.
A 39-year-old man and a 36-year-old man are due in court today charged with riotous behaviour and a police officer was taken to hospital with burns to the face, after his vehicle was set on fire by rioters.
Earlier Mr Adams said: "Today's meeting has an added urgency given the interface of violence in some parts of Belfast and given the siege that some small areas like the Short Strand have been subjected to in recent weeks.
Meanwhile in Bangor, Co Down a Catholic church was damaged after being attacked with paint bombs and a cross-community school was damaged by fire after an arson attack.
St Columbanus High School will remain closed today after the attack, except for Year 12 students who are sitting exams.
In north Belfast, a house was damaged by a blast bomb and in Carrickfergus, Co Antrim, British army technical officers dealt with a suspicious object found under a car outside a dealership. The object was found to be a hoax.
Work began yesterday to raise the height of the "peace wall" separating nationalist and loyalist areas in east Belfast, after some of the worst paramilitary and sectarian violence in years.
British army engineers were hoping to finish work on two sections of the interface in the Short Strand area by nightfall, but said it would be several weeks before the task was fully completed.
The wall is up to four metres high and is being increased by up to three and a half metres more in a bid to prevent missiles such as blast bombs and petrol bombs being thrown over.
The Northern Ireland Secretary, Dr John Reid, said there had been a very worrying involvement and orchestration of recent violence by paramilitaries on all sides. He expressed concern at the "general lack of confidence" in the peace process in the North.