Speaking in the House of Commons on Wednesday, John Reid appealed for calm during Protestant loyal order parades later this week.

He told MPs it would be a "potentially challenging and difficult weekend".

"I would appeal to anyone of any influence and authority to do all they can to make sure we come out of this weekend without the blight of violence that has too often scarred Northern Ireland," he said.

We will have to take steps to make sure that everyone recognises that there is no half-way house, there is no tolerable level of violence

John Reid

His remarks followed scenes of violence which followed Sunday's disputed Orange Order parade at Drumcree which was banned from marching along the mainly nationalist Garvaghy Road in Portadown, County Armagh.

There are disputes over a number of parades in Belfast on Friday - the Twelfth of July - which is the biggest day in the marching season calendar.

Government is determined

Dr Reid said new research showing a worsening divide between the communities made "depressing reading".

The secretary of state again emphasised there could be no "acceptable level of violence".

"In the longer term, yes we will have to take steps to make sure that everyone recognises that there is no half-way house, there is no tolerable level of violence which is acceptable in Northern Ireland.

"I will certainly do all I can to do that and I hope that other gentlemen and ladies on all sides of the house will do what they can."

Dr Reid said the government was determined to "as far as humanly possible" get advances in decommissioning and demilitarisation of paramilitary organisations".

This reached a new low when a cortege and hearse in Londonderry was pelted with stones and paint-bombed

John Reid

"This is something we have been trying to achieve in Northern Ireland since the origins of the state."

He said the government was seeking to complete decommissioning in the shortest possible time-frame.

He said the government had come a long way in counter-acting violence and maintained a security presence commensurate with the level of threat.

Dr Reid condemned an attack on a funeral cortege in Londonderry as "beneath contempt, the lowest of the low".

Overall numbers

Stones were thrown at the funeral procession and a police escort pelted with paint by a gang of youths in front of the dead woman's disabled daughter.

Addressing the role of trade unions in the peace process, Dr Reid said it was part of a spate of attacks on emergency services and bus drivers.

He said it showed violence had reached "a new low" in Northern Ireland.

Responding to a question from Ulster Unionist MP Jeffrey Donaldson, Dr Reid said the strength of the police was "beneath the level that we should be at".

"That is precisely why we are recruiting something like 50% more per annum than was envisaged in the Patten proposals themselves."

He said the Policing Board was looking at the overall numbers of police in Northern Ireland and he did not want to pre-empt that review.

Meanwhile, Prime Minister Tony Blair pledged to meet members of the Democratic Unionist Party after they were warned their lives were in danger.

Mr Blair said he would meet party leader Ian Paisley and his fellow MPs.

Mr Paisley said: "Each one of us have all had attempts on our lives in the past."

Mr Blair said: "Obviously we put forward protection for people on the basis of advice we receive - I cannot say any more than that about it and I do not think it would be sensible for me to speculate on the levels of threat."