A senior officer told a news conference in Yangon that a court martial was under way and that the verdict would be made public. The military also pledged help for the victims' families.

"The court martial found that they violated the rules, failing to follow certain procedures, that led to the death of the victims during the interrogation," said Deputy Major General and chief of military intelligence Mya Tun Oo.

Myanmar's armed forces have often been accused by human rights groups and Western governments of abuses during decades of conflict with ethnic armed groups.

Campaigners such as Amnesty International say it is extremely rare for troops to be held accountable for alleged abuses or for such allegations to be investigated transparently.

Witnesses have told Reuters soldiers rounded up dozens of men in the village of Mong Yaw in northern Shan State on June 25 and led five men away. The bodies of the five were found in a shallow grave a few days later.

The military's response suggests a heightened sensitivity about the army's image as it tries to present itself as a responsible partner in Myanmar's democratic transition and seeks closer ties with its Western counterparts.

"Every soldier has to follow rules and regulations while investigating prisoners or detainees regardless of whether they are related to insurgents or regular citizens," said Mya Tun Oo, adding that the military would take action against the perpetrators according to the law.

"The military will take the best care and support of the victims' families," added Mya Tun Oo, without giving the details.

The deaths of two other men in a separate incident were also being investigated, the military said.