YANGON (Reuters) - Myanmar’s security forces have now killed at least 26 people in response to attacks on police that have sparked a dramatic escalation in violence in a Muslim-majority region along its border with Bangladesh, according to reports in state media.

Police forces prepare to patrol in Maungdaw township at Rakhine state, northeast Myanmar, October 12, 2016. REUTERS/Stringer

Armed men believed to be from the long-oppressed Rohingya Muslim minority launched a coordinated assault on three border police posts in the early hours Sunday, killing nine police, injuring five and making off with dozens of weapons and more than 10,000 rounds of ammunition.

Military personnel and police reinforcements have poured into the Muslim-majority township of Maungdaw, northern Rakhine State, and have clashed with groups of up to 300 men, armed with pistols, swords and knives, according to official reports.

Human rights groups and advocates for the stateless Rohingya have voiced concern that the civilian population may be caught up in the authorities’ violent response.

Myanmar’s de facto leader Aung San Suu Kyi said that her government was “exercising the rule of law” in dealing with the attacks, the state-run Global New Light of Myanmar newspaper said on Thursday.

Authorities had not yet confirmed who was behind the attacks, Suu Kyi said on Wednesday.

The military’s official newspaper, Myawady, said that another 10 alleged attackers were killed, and a rifle was seized, in a clash on Tuesday morning at Kyetyoepyin village, Maungdaw Township.

In a separate incident on Wednesday, the military accused armed attackers of setting fire to 25 houses after an aborted attack on border police quarters in Kyikanpyin village, the site of one of Sunday’s attacks.

The killings bring the total death toll in northern Rakhine State since Sunday to 39, including 13 security personnel.

The 26 alleged attackers reported killed include several who a local resident told Reuters were shot while unarmed and fleeing soldiers.

Campaign group Fortify Rights said on Wednesday it had received reports of extrajudicial killings in the area and called on Myanmar’s government to “protect civilians regardless of religion or ethnicity.”

Authorities have also detained four men, identified as local Muslims, who they allege were involved in the attacks.

The Rohingya bore the brunt of intercommunal clashes in Rakhine in 2012, in which more 100 people were killed. They make up most of the 125,000 people still living in displacement camps in Rakhine State and face severe restrictions on their movements.