YANGON, Burma -- Burma's government on Sunday reported fierce fighting in the western state of Rakhine, where the army has been conducting counterinsurgency operations since nine police officers were killed in attacks on posts along the border with Bangladesh last month.

The fighting, reported in an Information Ministry statement, comes as human rights groups have been accusing Burma's army of abuses against civilians of the Muslim Rohingya ethnic minority, especially since last month's attacks. Recent reports accuse soldiers of killing, raping and burning the homes of the country's long-persecuted Rohingya.

The statement said government troops were ambushed Saturday morning by about 60 attackers armed with guns, knives and spears. It said one soldier and at least six attackers were killed, adding that an army officer died in a later battle against 500 armed men, which ended when two air force helicopters joined the fight.

The attackers weren't identified, but the army has aligned with Rakhine Buddhists against Rohingya since violent intercommunal conflict erupted in 2012.

More than 100,000 Rohingya are still in squalid camps for the internally displaced after being driven from their homes in 2012. Although many have lived in Myanmar for generations, they are widely regarded as illegal immigrants from Bangladesh, and the government denies citizenship to most of the million or so Rohingya.

On Friday, the U.N.'s special representative on sexual violence in conflict called on Burma to investigate allegations of sexual assault in northern Rakhine state. Zainab Hawa Bangura said it was essential for the government to allow humanitarian access to the area to provide support for the survivors.

The Information Ministry statement said that the attackers set fire to a village as they retreated. However, human rights groups have been accusing government forces of burning down Rohingya villages.

The statement said troops arrested 36 men believed to be among Saturday's attackers.

Independent confirmation of the events is difficult, because the area is remote and the government discourages access. There has been no credible description of what, if any, organized force has been fighting against the government.