High-level negotiations are taking place to solve an impasse at the international tribunal set up to investigate the 1994 genocide in Rwanda.

Carla Del Ponte, the tribunal's chief prosecutor, met Rwandan President Paul Kagame in the Rwandan capital Kigali on Friday but refused to answer questions from journalists afterwards.

Del Ponte did not get a warm welcome in Kigali

Two major trials were postponed this week at the tribunal in Arusha, in neighbouring Tanzania, because prosecution witnesses were unable to travel from Rwanda.

Tribunal officials accuse the Rwandan Government of introducing new travel regulations designed to stop witnesses attending.

This has been denied by the authorities in Kigali, who say that the new regulations apply to all foreign travel, not just to Arusha.

No witnesses

But observers suspect that they may be trying to obstruct the Arusha tribunal after genocide survivors withdrew their co-operation earlier this year.

On Wednesday, the tribunal's single biggest trial was postponed until October because no prosecution witnesses had turned up.

Six people, including former Family Affairs Minister Pauline Nyiramasuhuko, are accused of organising massacres in Butare.

Around 800,000 people were killed in 100 days of slaughter

The trial of former Information Minister Eliezer Niyitegeka was also put back - until August - for the same reason.

On Thursday, hundreds of genocide survivors held street protests in Kigali to coincide with Ms Del Ponte's visit.

They are unhappy at the slow prosecution rate at the International Criminal Tribunal for Rwanda.

In seven years, eight people have been convicted and one man acquitted.

In January, the Ibuka and Avega associations of genocide survivors stopped co-operating with the Arusha tribunal.

They also claim that some genocide suspects are working for the tribunal.

'Hate media'

"What they protect is their jobs and fat pay cheques, not the interests of victims," one demonstrator shouted.

"When witnesses return from recording secret testimony at the court in Arusha, they find that relatives of suspects and everyone else in the village knows exactly what was in the testimony," said Philibert Gakwenzire, an official with Ibuka.

On Monday, the "hate media" trial is due to start.

Professor Ferdinand Nahimana and Jean-Bosco Barayagwiza are said to have been instrumental in setting up a private radio station, Radio Tele Libre Mille Collines (RTLM), which urged ethnic Hutus to kill Tutsis.

A third man, Hassan Ngeze, is also accused of contributing to the massacres, through the Kangura newspaper, which he edited.

Around 800,000 Tutsis and moderate Hutus were killed over 100 days before Paul Kagame's Rwandan Patriotic Front took power in 1994.