Three Indonesian soldiers arrested for raping four women in war-torn Aceh province have confessed to the crimes, the military said.

The private soldiers are now being detained at military police headquarters in North Aceh, said military operations spokesman Lieutenant Colonel Yani Basuki.

The rapes took place separately between June 20 and 22. "According to the soldiers and the victims, the rapes indeed happened," Basuki told AFP Monday. The troops could face 12 years in jail if found guilty at a later hearing.

It was the second time rapes had been reported since the military and police on May 19 launched an all-out assault to crush Free Aceh Movement separatist guerrillas, who have been fighting for independence since 1976.

Earlier in June a police paramilitary soldier was been detained for allegedly raping a 15-year-old girl.

The military, which has a record of gross rights abuses during earlier campaigns in Aceh, has said it will try to ensure its troops behave better this time. Six soldiers have been jailed for between four and five months for beating up civilians during a hunt for rebels.

However, martial law authorities have restricted travel in the province by foreign media and overseas non-government organisations, making independent monitoring of rights abuses difficult.

Explosions rocked two markets in the provincial capital Banda Aceh early Monday, injuring three hawkers. The first blast occurred at the Aceh Shopping Center at around 7am, damaging several kiosks but causing no injuries. The second blast at the nearby Kampung Baru market some 30 minutes later injured three traders, said Banda Aceh city police chief Alfons Tololuhula said. "They were home-made, low explosive, bombs," Tololuhula said, accusing separatist rebels of planting the bombs the previous evening "as a form of terror to scare the population."

Villagers said they found the bodies of a young couple with gunshot wounds early on Monday. They said two armed men believed to be rebels were seen taking the couple from their home at Lam Teungoh in Aceh Besar district around the capital the previous evening.

The military says at least 270 rebels have been killed since the start of the offensive for the loss of about 30 police or troops. Local rights group Kontras has said 176 civilians had been killed as of the middle of June but did not say by whom.