A Myanmar insurgent group said it has buried the remains of more than 30 people who were killed and had their bodies set ablaze, as the UN Security Council called for accountability and an immediate end to violence in the country.

Opposition activists have blamed Myanmar's army for the Dec 24 attack near Mo So village in Kayah State in which the Save the Children aid group said two of its staff were killed.

A spokesman for the junta has not commented on the attack but state media in military-run Myanmar has previously reported that soldiers had fired on and killed an unspecified number of "terrorists with weapons" in the village.