Dozens of civilians, including Buddhist monks, have been shot dead at a monastery in eastern Myanmar.

The killings came after the military attacked a village in Shan State on Saturday with airstrikes and artillery. Pro-democracy forces have blamed junta soldiers for the massacre.

The pro-democracy camp released a statement about the incident on social media.

It says when their fighters advanced on a monastery in the village, they saw junta troops herd 30 villagers and three monks out of the building, stand them against a wall and shoot them.

It says 28 people, including monks, were confirmed dead at the scene the next day.

The military has not commented on what happened.

The deputy head of Human Rights Watch in Asia pointed out Myanmar's military is accused of killing at least 263 civilians since December.

Phil Robertson said the increase in what he called "brutal massacres in Myanmar" shows that "the junta commanders have given the green light to their troops to indiscriminately attack civilian targets without hesitation."

He called on the international community to impose sanctions on the military to "stop these atrocities" immediately.