Myanmar security forces killed three people while clearing a suspected Rohingya insurgent training camp in the mountains in the troubled northwestern state of Rakhine, the state-run Global New Light of Myanmar daily said on Thursday.

The authorities conducted "area clearance operation" over the last two days, uncovering a tunnel, homemade weapons, huts, rations, utensils and other items used by the militants in the training, the newspaper said.

More than a million Muslim Rohingya live in apartheid-like conditions in Rakhine, where many majority Buddhists consider them interlopers from Bangladesh. The insurgent group was not immediately available for comment.

The insurgents attacked border guard posts in October, provoking a military crackdown in which hundreds were killed, more than 1,000 houses burned down and 75,000 people forced to flee to Bangladesh.

The United Nations has established a fact-finding mission to investigate crimes against humanity allegedly committed by the security forces during the counter-offensive. The administration of Nobel Peace Prize laureate Aung San Suu Kyi has rejected the allegations and opposes the mission.

Photos published on the newspaper's front page showed materials found at the site, in the remote Mayu Mountain range, including 20 black skiing masks, gun powder and long wooden guns believed to have been used during the training.

In March, Reuters described how a small group of Rohingya leaders recruited several hundred young men in the run-up to the October offensive, teaching them karate and training them with wooden guns.

One man who attacked security forces inside the 80-feet (24.4-metre) tunnel with a machete was "killed in self-defence" on Tuesday, the paper said, while two men were killed on Wednesday.

The operation continues.