Blair: Get N. Ireland 'sorted'

Blair and Ahern hope to avoid the collapse of the Northern Ireland Assembly

LONDON, England (CNN) -- UK Prime Minister Tony Blair has urged immediate progress on Northern Ireland's fragile peace process.

After a meeting at his country residence, Chequers, with Irish counterpart Bertie Ahern, Blair told reporters: "It's got to be done now. There is no point in people thinking this is going to change in August or September and October.

"We need to settle down, get the hard work done and get the thing sorted."

The two leaders then moved to a secluded house in the English Midlands for a two-day summit with heads of Northern Ireland's political parties in an attempt to prevent the collapse of the devolved government after the resignation of First Minister David Trimble last week.

AUDIO 'Leaders hoping to save power-sharing assembly' 784 KB / 1 min 11 secs AIFF or WAV sound   MORE STORIES Q&A: Tension at Drumcree

Trimble's Protestant, pro-British party, the Ulster Unionists, have threatened to withdraw from the local administration unless the Irish Republican Army (IRA) begins to disarm.

Trimble resigned his post in protest over the IRA's refusal to hand over weapons.

By law, the British and Irish governments have until August 12 to come up with a solution acceptable to the political parties in the assembly.

If no agreement is reached, London will have to either suspend the assembly or call fresh elections.

Ahern was optimistic this week's talks would yield results.

"This is the week where we can try to finish the outstanding issues. Over these next few days, if we work together ... I believe we can come to a successful conclusion."

Previously staged Northern Ireland negotiations have taken place under a round-the-clock media spotlight, but Blair decided the latest diplomatic push should be staged in Weston Park, a grand 17th-century residence isolated in private gardens and a forest.

Journalists were barred from the scheduled two-day talks.

The talks on Monday come as police in the Irish Republic discovered weapons including 20 mortars and 20 rockets at two sites.

Tensions ran high at Dumcree during the weekend

The weapons are being linked to the Real IRA, a group opposed to the peace process.

Trimble said the peace process was slowly collapsing because of the IRA's refusal to disarm.

"We are approaching, I think, what may very well be the moment of truth for this entire process," Trimble told BBC radio.

"Either we see republicans keep the agreement, or else we are going to have to conclude that this process can't work."

Sinn Fein leader Gerry Adams has said the arms issue must be resolved as part of a wider debate, including policing issues and republican demands for scaling down the British military presence in Northern Ireland.

"The process has become lost and it has to be put back on to the right road. That is certainly our intention in coming here," he said when he arrived at the talks.

There was also some minor overnight violence at Drumcree, Northern Ireland, where authorities had earlier kept a controversial Protestant Orange Order march from its intended route.

Massive security measures on Sunday to prevent violence seemed to have paid off, after about 2,000 members of the Orange Order marched through Drumcree.

The annual Drumcree parade came to a halt when marchers arrived at a steel barricade, preventing them from going down the mainly Catholic Garvaghy Road.

The Parades Commission had banned the parade from the road in Drumcree for the fourth consecutive year.

The Orange Order handed in a letter of protest when they arrived at the barricade, and the grand master appealed for calm and for the marchers to disperse.

The annual Drumcree Orange March has in recent years been one the most contentious parades of the marching season in Northern Ireland. It comes at a time when sectarian tensions are running high and the future of the Good Friday Agreement is under threat.

Predominantly Protestant areas of Northern Ireland remained largely calm overnight, and police forecast little unrest in the run-up to bigger Orange parades on Thursday.