Sudan's President Omar al-Bashir has criticized the U.N.-African Union peacekeeping mission in Darfur as tensions rise over the joint force's investigation into alleged mass rape by government-backed fighters.

The state-run Radio Omdurman on Monday quoted al-Bashir as saying that the mission, known as UNAMID, "has become a security burden on the armed forces."

Al-Bashir also accused UNAMID of "impartiality" and "falsifying facts."

Tensions have been rising after the mission sought to investigate allegations that more than 200 women were raped by forces allied to the government in the north Darfur village of Tabit. Al-Bashir says the investigation will not be allowed to continue.

Last week, Sudan asked the joint force to shut down its human rights office in the capital Khartoum.