Rwanda's Supreme Court postponed the hearing of a plea seeking the release of former Congolese Tutsi rebel chief Laurent Nkunda, a statement from Nkunda's family said Thursday.

Nkunda's lawyers in December complained to the Supreme Court that their client's continued detention, first in Gisenyi, a town in north western Rwanda on the border with DR Congo, and then in Kigali, was "illegal".

Presiding judge Aloysie Cyanzaire said Rwanda's chief of defence staff James Kabarebe - subpoened to attend Wednesday's hearing on "the illegal detention of Laurent Nkunda" - would be available on February 26 at the earliest.

"Consequently, the court's president delayed the hearing until March 1, 2010, more than 45 days from today during which Laurent Nkunda will unfortunately remain in detention," the statement said.

Nkunda was arrested in Gisenyi on January 22, 2009, when he was head of a rebel National Congress for the Defence of the People (CNDP) group, according to people close to him.

In October 2008 Nkunda's men routed the Congolese army in North Kivu province and threatened to take the strategic town of Goma.

But after a shift in alliances the Congolese and Rwandan armies on January 20 launched an unprecedented joint operation targeting Rwandan Hutu rebels in eastern DR Congo which also resulted in Nkunda's arrest.