Myanmar's military government has arrested two more local journalists, the army-owned television reported on Saturday, in the latest in a sweeping crackdown on the media since a February 1 coup.

Sithu Aung Myint, a columnist for news site Frontier Myanmar and a commentator with Voice of America radio, and Htet Htet Khine, a freelancer who has worked for the BBC Burmese service, were arrested on August 15, Myawaddy TV reported.

Sithu Aung Myint was charged with sedition and spreading false information in social media posts that Myawaddy said were critical of the junta and urged people to join strikes and back outlawed opposition movements.

Htet Htet Khine was accused of harbouring Sithu Aung Myint, a wanted criminal suspect, and for working for and supporting a shadow National Unity Government.

Reporters Without Borders (RSF) said on Saturday that the pair were being held "incommunicado" and their detention was unlawful.

"We strongly condemn the arbitrary conditions of their detention, which reflect the brutality with which the military junta treats journalists," said Daniel Bastard, head of RSF's Asia-Pacific desk.

Myanmar remains fraught with instability and opposition to army rule, under which more than 1,000 people have been killed, according to an activist group that has tracked killings by security forces.

The military, which has revoked the licenses of many news outlets, says it respects the role of media but will not tolerate the reporting of news it believes to be false or likely to create public unrest.

A report by the Committee to Protect Journalists last month said Myanmar's rulers had effectively criminalised independent journalism.

Human Rights Watch said the army government, which has arrested 98 journalists since the coup, stop prosecuting media staff. Of those arrested, 46 remained in custody as of the end of July.