Justice Louise Arbour is leaving to join Canada's Supreme Court just two weeks after she issued a controversial indictment of Yugoslav President Slobodan Milosevic for crimes against humanity.

Her investigators are poised to enter Kosovo to seek evidence of war crimes committed by Serbian and Yugoslav forces.

Mrs Arbour: Said to be feeling the strain

Canadian Justice Minister Anne McLellan said Mrs Arbour was delaying taking up her new post until 15 September to ensure "continuity in the work of the war crimes tribunal".

A new chief prosecutor will be chosen by the UN Security Council, which created the tribunal in 1993 to investigate war crimes in the former Yugoslavia.

The BBC's correspondent in The Hague, Gillian Sharpe, said the move signals a period of great uncertainty for the tribunal.

Mrs Arbour has been a valuable public face for the tribunal and has proved adept at dealing with the international political world.

Feeling the strain

Mrs Arbour, a criminal law specialist and veteran judge from Ontario, joined the tribunal in October 1996.

She has gained a reputation as a fiercely independent prosecutor - which has made her unpopular in diverse political circles.

Her appointment to Canada's nine-member Supreme Court had long been rumoured.