The United States has expressed concern over an escalation in violence in Sudan's troubled Darfur region, after rebels captured a southern village.

A State Department spokesman said Wednesday both rebels and the government-backed militia have contributed to the increase in violence in Darfur.  He said African Union cease-fire monitors are critical to bringing the situation under control.   

Monday, the rebel Sudan Liberation Movement violated a cease-fire and launched a surprise attack on the town of Sheiria.  The Sudanese government has threatened to retake the town.

Rebels have also recently accused the government-backed militia of incursions into rebel-held territory.

The violence comes during a sixth round of African Union-sponsored peace talks between Darfur rebel groups and the Sudanese government. AU officials said the renewed fighting could mar the talks and urged both sides to exercise restraint.

Some information for this story provided by AFP and Reuters.