YANGON (REUTERS) - Last week's arrest of an NGO worker in Myanmar for a Facebook post is raising fears that legislation drawn up as part of the country's economic and democratic liberalisation are being used to stifle dissent in ways reminiscent of laws drafted by the former military junta.

Myanmar only began to regain its freedoms of expression from 2011 after 49 years of military rule, and critics fear the arrest of Patrick Kum Jaa Lee for commenting on a picture showing a foot standing on a photo of commander-in-chief Min Aung Hlaing is a worrying backward step.

He is being charged under Myanmar's telecommunications law, enacted in 2013 as part of an opening up of the telecoms sector. The act contains a broadly worded clause that prohibits use of the telecoms network to "extort, threaten, obstruct, defame, disturb, inappropriately influence or intimidate".

Under that clause, Patrick Kum Jaa Lee faces up to three years in prison. His arrest is part of a wider crackdown on social media posts deemed offensive to the military and government in the run-up to an election on Nov 8.

At least two other Facebook users have been arrested in recent weeks.

May Sabe Phyu, Patrick Kum Jaa Lee's wife, who visited him on Monday at Yangon's infamous Insein Prison, where he is being held before a court appearance next week, said the charges were"ridiculous" and the law was not being applied even-handedly.

"What about the other people, who are attacking (opposition leader) Daw Aung San Suu Kyi, sharing hate speech, attacking Muslims online?" she said.

The telecommunications law was a key piece of legislation in President Thein Sein's push to modernise Myanmar's outdated telecoms sector, which had been monopolised by state-owned Myanma Posts and Telecommunications (MPT) under the junta.

Mobile penetration and internet use have since soared, and Facebook is wildly popular.

Thein Sein has touted the mobile expansion as a major achievement of his administration in election campaign videos.

A report on the telecoms sector from the Myanmar Centre for Responsible Business published earlier this year warned that the telecoms law could be used to curb freedom of expression. "These are vague terms that are not defined in the law. This creates a clear risk that the Myanmar Government could use the 2013 Telecommunications Law to arbitrarily characterise legitimate expression as 'threats' or an 'inappropriate influence', punishable as a criminal offence," the report said.

A government spokesman could not be reached for comment. Colonel Win Bo, deputy director of the Yangon Region Police, said he did not have any specific information on the case.