Citing sources in London and Washington, The Observer said that six weeks was considered by military planners as the minimum period necessary to wear down Serb military and police units in the Yugoslav province so that they offered only limited resistance. ``We are no longer talking about simply sending peace-keeping troops into an entirely permissive environment,'' said one unidentified source quoted by the paper. ``We are talking about the use of ground forces in a way that would have been complete taboo a month ago. That is, sending troops in semi-opposed.''

The Observer said that despite repeated denials in London and Washington of plans for a ground invasion, such proposals were being rushed ahead to wrap up the military campaign in the three months since it began on March 24.

A NATO official in Washington told the paper that theground assault would have two levels: the invasion of Kosovo, and the containing of Serbia and the region around Belgrade by a further 200,000 troops in addition to the invasion force.

Between 75,000 and 80,000 troops had been earmarked for the invasion, said The Observer, adding that some US soldiers had already begun training in reconstructions of a Balkan village in the Colorado Rockies. The force would be preceded by an advance guard of 20,000, including reconnaissance and special forces, mine-sweeping and explosives experts, followed by an artillery and tank spearhead.

A further 200,000 troops would be used for the securing of the Federal Republic of Yugoslavia's other borders with Bosnia, Hungary and Romania ``to all but throttle Serbia and to cage Milosevic''.

A Romanian diplomat in Washington reportedly confirmed to the paper that US officials had made preliminary overtures to discuss such a mass deployment of troops.

A US official was quoted as saying that the timing of the invasionwould be ``no sooner than six weeks, but not necessarily later than two months'' and would depend on when the weather was more reliable.

The Observer said one of the aims of the air strikes until troops were ordered into Kosovo, would be to cut Serbian communication and logistic support to the point of being negligible.

``Already we are seeing evidence that this is happening,'' said the source.

``The main road between Belgrade and Pristina along which the Serbs could reinforce has been cut. They are running out of diesel and petrol in the province, and we are hearing reports that when Serb troops use their radios they are not working. We are also hearing reports of collapsing morale in the Pristina Corps, including defections,'' the source added.