A renowned Thai scholar faces possible charges of lese majeste over comments about a king who reigned more than 500 years ago, sources said Tuesday.

Sulak Sivaraksa was accused last week by two retired army officers of insulting King Naresuan, a renowned 17th-century monarch.

The officers were reportedly irked by Sulak's comments doubting the authenticity of the tale of a famous elephant battle, during which Naresuan is said to have defeated a Burmese prince.

According to a source close to Sulak, the academic had merely questioned the authenticity of parts of Naresuan's legend, and pointed out some negative aspects of his 1590-1605 reign.

"His comments were purely academic, completely in line with what scholars do," the source said, noting that the threat of legal action was "worrying."

A government spokesman declined to comment, saying that the case has not yet been accepted by the courts and must go through the proper legal channels first.

Thailand's lese majeste laws are designed to protect the monarch, his consort and his heir from insult.

Critics have argued that the law is abused by various parties to achieve political ends.

Since coming into power in May coup, the military has implemented its own interpretation of the laws.

Dozens have been arrested and sentenced, including a taxi driver who received a two-year jail sentence for a comment he made to a passenger in conversation.