The BBC's Jackie Rowland reports from Belgrade

The Kosovo Liberation Army says the grave lies between the towns of Urosevac and Stimlje in territory under Serbian control.

Observers were given pictures of the site during a meeting with KLA representatives on 30 December. At the time, the reports could not be verified because of bad weather.

A spokesman for the international monitoring mission in Kosovo admitted that the human rights workers would probably only be able to look at the alleged grave site and see if there were any obvious signs.

The mission has no facilities for carrying out forensic tests. A team of pathologists from Finland which was in Kosovo investigating another mass grave is currently out of the country.

The October agreement has looked shaky

The BBC Correspondent in Belgrade, Jackie Rowland, says the reports of the alleged grave near Urosevac have once again demonstrated the monitors' limitations.

The mission went to Kosovo with a mandate to police the ceasefire between the ethnic Albanian rebels and the Serbian security forces.

Within a short time it has found itself taking on a number of tasks more often associated with humanitarian agencies.

This latest task is particularly sensitive, since reports of a mass grave could endanger the shaky ceasefire which was re-established only last week.

There has been sporadic fighting in Kosovo since the truce declared in October, notably intense clashes between 24 and 27 December.

The Organisation for Security and Co-operation in Europe is still assembling its force of 2,000 international monitors, which hopes to help prevent a return to full-scale fighting.