There is nothing to suggest the IRA orchestrated recent violence in east Belfast, Sinn Fein leader Gerry Adams has said.

He was speaking in Downing Street after talks with Prime Minister Tony Blair on Monday.

The sectarian clashes in the east of the city topped the agenda at the talks, which lasted just over an hour.

He said the root of the violence was problems within the unionist community

Tony Blair: Concerns over violence

"This is the crisis within unionism manifesting itself in sectarian attacks on vulnerable nationalist communities," he said.

"And I told the prime minister that what is happening in the beleaguered community of the Short Strand reaches back here into No 10 Downing Street.

"The government has to ensure that no-one thinks there is any alternative to the Good Friday Agreement or the changes which it contains.

"So I think there is a need for all of us to knuckle down, and try and get a calming influence."

Last week, new security measures were announced by Northern Ireland Security Minister Jane Kennedy after a week of disturbances in which several people were injured by gunfire across so-called peace lines in east Belfast.

Several families on both sides moved out of their homes following attacks.

Both communities have blamed each other for the violence.

Policing experts

Secretary of State John Reid has said there is evidence that paramilitaries on both sides had been orchestrating violence.

On Sunday, shots were fired and petrol bombs thrown after police came under attack from rival crowds in south Belfast.

The trouble began when bottles and other missiles were thrown in the Donegall Pass area of the Ormeau Road.

Police later seized two crates of petrol bombs at Walnut Street in Donegall Pass.

In east Belfast, soldiers began work on raising the height of the interface wall between the Protestant Cluan Place area of the Albertbridge Road and the Catholic Clandeboye Drive area in Short Strand.

The Army said the wall - currently up to 4m high - would be increased by up to a further 3.5m.

Members of the Northern Ireland Assembly roundly condemned the recent trouble at Monday's sitting at Stormont.

The first and deputy first ministers said: "We utterly condemn and will seek to counter sectarianism wherever it occurs."