Banda Aceh – Indonesian police opened fire and killed five people in the restive province of Aceh, just four days prior to the 25th anniversary of the separatist Free Aceh Movement (GAM), residents said Friday.

Five men believed to be GAM members were killed in a firefight with police on patrol in the Seulimuem area of Aceh Besar district late on Thursday, said police operational spokesman Superintendent Yatim Suyatmo.

Suyatmo said the rebels had attacked a convoy of elite police Brimob troops that was trying to pick up Pidie district police chief Superintendent Heru Budi Ersanto at the Sultan Iskandar Muda airport here. However local residents told AFP that the five were among a group of seven unarmed civilians who had been travelling from the town of Seulimeum to the town of Saree in a van.

"The seven had pulled over the van to change the car's driver when the convoy passed them by ... they opened fire and killed one man on the spot while the other six were herded into police truck and taken to Alue Rindang area," a resident said on condition of anonymity. "The six were then ordered to get out of the truck and run, police opened fire and killed four men, two others somehow managed to escape," the resident added.

Meanwhile in anticipation of GAM's 25th anniversary plan on Monday, police and troops tightened security across the flood-stricken province by putting more convoys on the streets, witnesses said on Friday.