In a speech to Russian armed forces commanders, Mr Sergeyev said Russia had seen an expansion of "intra-state terrorism funded and directed from abroad".

He said the US intended to "weaken Russia" and "establish full control over the North Caucasus".

According to the Russian news agency Tass, Mr Sergeyev said the global military and political situation was "extremely unstable in 1999".

He added: "The national interests of the United States would be met if a conflict fanned from outside smouldered permanently in the North Caucasus."

He attributed much of the instability to Nato's new concept based on "a stake in the use of force, disregard for the universally recognised norms of international law, diktat and arbitrariness".

Mr Sergeyev said what he called the "armed aggression of the United States and Nato against Yugoslavia" was a challenge to Russia.

'Discussion blocked'

The meeting of Russian Armed Forces Commanders was attended by Prime Minister Vladimir Putin and the president's chief of staff Alexander Voloshin.

British Foreign Secretary Robin Cook: "This is going to complicate relations with Europe"

Earlier, Russia and China blocked discussion of the Chechen conflict at the United Nations Security Council.

Concerned at reports of civilian casualties and the plight of refugees in the breakaway republic, Canada had requested that a UN humanitarian team be sent to the regional.

Canada had won support from five other members of the Council to put the matter on the agenda, but its initiative was strongly opposed by Russia and China.

The BBC's Mark Devenport at the UN: Conflict again reveals the limits of the international community's capacity to intervene

Both nations insisted that the violence in Chechnya was an internal Russian matter and not relevant to a body which deals with questions of international peace and security.

Canadian UN envoy Robert Fowler said his country respected Russia's sovereignty and territorial integrity.

But he said Canada believed that, in view of council concern for matters such as the protection of civilians in conflict, there ought to be "a broader discussion in the council of proportionate response with respect to the objectives of the Russian Federation in Chechnya".

"Clearly there were implications here that could affect international peace and security," Mr Fowler said.

Helsinki talks

Russian Foreign Minister Igor Ivanov has said Russia is "prepared to end the military actions even tomorrow" - but only if Chechen rebels surrender. This is a condition the Chechens will not accept.

Mr Ivanov is in Helsinki where he is discussing the issue with Norway's Knut Vollebaek, the chair of the Organisation for Security and Co-operation in Europe (OSCE).

During the talks, Mr Ivanov said the OSCE could help provide humanitarian aid to Chechnya but he rejected a mediation role for the European security body.

The question of whether the OSCE would be allowed a presence within the conflict zone, where it had played a role in negotiating an end to the 1994-96 war, had been raised by Mr Vollebaek.

An OSCE mission had cut short a visit to the northern Caucasus on Thursday, after Moscow refused the team entry into Chechnya on the basis that it had come on a humanitarian mission.