Fears are mounting that two priests have been killed by Myanmar's army after they disappeared on Christmas Eve.

Dom Dawng Nawng and La Jaw Gam Hseng from Mong Ko were arrested on December 24 after they went to a nearby military base to secure the release of a detained couple. The army released the couple but held the two priests who have not been seen since, according to Morning Star News.

The two Catholics had helped journalists from the former capital Yangon to report on the bombing of a church in early December. They were said to have enraged military officials by taking reporters to visit a damaged school in Mong Ko as well as the bombed church building destroyed in heavy fighting between the army and the coalition of ethnic armed groups.

"They went to negotiate for the couple's release," one source said, according to the Morning Star News. "The Burma army released the couple but detained the priests. I strongly believe that they got killed."

Fears escalated after widespread coverage of their disappearence did not secure their release, despite the army usually responding to negative media coverage.

Sources have told the persecution news site that if the priests were alive they would have been released in response to the extensive coverage.

"It is almost certain that they got killed," said one journalist who was shown around the bombed sites by the priests.

Heavy fighting broke out in Mong Ko between the national military and the ethnic separatist forces in November, leading to more than 50,000 refugees flee. The military have since claimed they have taken the area and urged refugees to return.