Hackers attacked military-run government websites in Myanmar Thursday as a cyber war erupted after authorities shut down the internet for a fourth straight night.

A group called Myanmar Hackers disrupted multiple government websites including the Central Bank, Myanmar Military's propaganda page, state-run broadcaster MRTV, the Port Authority, Food and Drug Administration.

The move comes a day after thousands of people rallied across the country to protest against a military coup that toppled Aung San Suu Kyi's civilian government from power earlier this month.

"We are fighting for justice in Myanmar," the hacking group said on its Facebook page.

"It is like mass protesting of people in front of government websites."

Cybersecurity expert Matt Warren from Australia's RMIT University said it was likely the aim of the hacking was to generate publicity.

"The sorts of attacks they would be undertaking are denial of service attacks or defacing websites which is called hacktivism," he told AFP.

"The impact will be potentially limited but what they are doing is raising awareness."

Another internet shutdown began in Myanmar at about 1:00 am on Thursday (1830 GMT Wednesday), according to NetBlocks, a Britain-based group that monitors internet outages around the world.

It said internet connectivity had dropped to just 21 percent of ordinary levels.