Four more former Rwandan government ministers are on trial at a U-N war crimes tribunal in Tanzania, charged with masterminding the 1994 genocide.

The four former ministers are charged with seven counts each related to genocide and other violations of the Geneva Convention. The four men have denied the charges.

A spokesman for the U-N International Criminal Tribunal for Rwanda, Bocar Sy, says the trial should be a welcome development for Rwandans.

"It is very important for them to see that these masterminds of the genocide are now on trial."

The accused are former Interior Minister Edward Karemera, former Minister of Primary and Secondary Education Andre Rwamakuba, the former Director-general of Foreign Affairs Mathieu Ngirumpatse, and the former Speaker of the Rwandan Parliament Joseph Nzirorera.

This is the second group of former ministers to appear before the tribunal. The trial of another group of four began at the start of November, and is still going on.

The tribunal was set up shortly after Rwanda's 1994 genocide, in which Hutu extremists killed more than 800-thousand Tutsis and moderate Hutus.

The tribunal has been criticized for being too slow to bring alleged perpetrators to justice.