Several former Soviet states on Monday proclaimed their support for a US-led military effort in central Asia, while Turkey agreed to grant the US landing rights for aircraft, but denied rumours that the country would be the headquarters for any US operation.

Kazakhstan's President Nursultan Nazarbayev said his country would support the US-led war on terrorism "with all the means it has at its disposal".

He indicated co-operation with the US could include the use of military bases and airspace, agencies reported, though he said no concrete requests had yet been received. Kazakhstan is close to Afghanistan but does not border it.

In Tajikistan and Uzbekistan, both of which have common borders with Afghanistan, rumours were swirling on Monday about actual or planned US deployments. It has been widely reported, though not officially confirmed, that US cargo planes have already delivered intelligence gathering equipment to Uzbekistan.

In Tajikistan, the government denied Russian and Iranian media reports on Monday that the US had also started bringing in equipment and possibly men. A Russian television station said US technicians had arrived from Uzbekistan to assemble electronic equipment for guiding US bombers into Afghanistan. The Tajik foreign ministry said the US had not yet asked to move in equipment or men, nor had it done so.

Fears of a refugee crisis continue to trouble Tajikistan. But so far there has been no new flood of them to the border, which is sealed by Russian troops, officials say.

The International Red Cross has said the main new flows of Afghan refugees so far have been heading towards Pakistan, where more than 15,000 may have entered last week.

The increasing likelihood that central Asian countries will play a vital role in any US strike on Afghanistan, comes amid signs that Russia, the dominant power in the region, has also decided to co-operate more actively with the US anti-terrorist campaign.

President Vladimir Putin appears to have over-ruled the greater reluctance and scepticism of his military chiefs.

Russia may also be conscious that it could not easily stop Uzbekistan and Kazakhstan backing the US even if it wanted to. It has more control over Tajikistan through its heavy troop presence there.

Another former Soviet state, Ukraine, on Monday cleared the way for US military cargo planes involved in anti-terrorist operations to fly through Ukrainian air space.

Members of Ukraine's national security council announced the decision after a meeting on Monday chaired by President Leonid Kuchma. The council members said they were granting an official US request.

In a related move, Turkey, a staunch Nato ally on the Middle East's doorstep, has agreed to a US request for "expedited overflight" rights and for the right to land aircraft bound for destinations unknown. Officials dismissed reports Donald Rumsfeld, US defence secretary, was going to ask Turkey to serve as the command centre for the operation.