Geoff Hoon has set out plans to establish a 6,000-strong reaction force to support the civil emergency authorities if terrorists pull off a "spectacular" in the UK.

The troops, to be drawn from the volunteer reserves of the Royal Navy, Royal Marines, Army and Royal Air Force, will form a dedicated unit to assist the emergency services.

Volunteer reservists would play an "important role'' in meeting the challenges posed by the international war on terrorism, the defence secretary said.New proposals outlined in a consultation document will draw the new force from the 50,700 existing part-time volunteer reservists, who will continue to serve with their normal units.

Held at a state of "graduated readiness'' the volunteers will assist the civil authorities within hours of a terror strike.

Police and emergency services will be boosted by "trained, disciplined personnel" should an atrocity occur.

The part-time troops would be used to assist in dealing with mass casualties, site search and clearance.

They would also provide support with transport, communications and assist with moving thousands of people in crisis conditions.

The new force will also head up command and control facilities with the ability to function in the event of a nuclear, biological or chemical attack.

The Tories said the new force must be backed up by an expansion of the territorial army and extra resources for the already stretched armed forces.

Shadow defecne secretary, Bernard Jenkin, said: "If the government is now committed to expanding the TA instead of cutting it, this is very good news.

"It was clearly a mistake when Labour cut the TA and Reserves in their 1998 defence review."He is concerned that Britain's capacity to cope with a September 11 style attack is behind America."However, this is just another consultation. The UK is miles behind the US and other countries on the issue of homeland defence. And are these new measure matched by new money?," he said.

"The present commitments of the armed forces already outstrip resources - will this simply add to overstretch?"

MoD sources have rejected the comparison with America, stressing that three decades of the Irish troubles had developed a strong capacity to deal with terrorism.

Security experts have also expressed unease at the plan - stressing that it does not go far enough.

They have suggested that a Department for Home Defence, similar to the new American Department of Homeland Security, should be established to tackle the new terror threat.