Police in southern China say they have arrested 25 people after a clash between street vendors and security forces, the second such recent incident highlighting government difficulties controlling widening social unrest.

Police say the arrests were made following a dispute between a migrant couple, who are street vendors, and security forces in Xintang town near Guangzhou city on Saturday night.

A statement posted Sunday on the Guangzhou police website said "troublemakers" blocked traffic and damaged vehicles, forcing police to "adopt measures to prevent the incident from further escalating."

Also Saturday, paramilitary police patrolled the streets of Lichuan in Hubei province in central China following a riot over the death of city councilman in police custody.