Myanmar lost access to Twitter on Friday night, the latest move to stifle dissent as the military widened an internet ban days after a coup that has drawn global condemnation and the threat of new sanctions.

De facto leader Aung San Suu Kyi was detained Monday and ousted from power, returning the country to military rule after a 10-year dalliance with democracy.

Facebook was the first platform that saw issues on Wednesday. By Thursday, Myanmar users had flocked to Twitter to spread a hashtag campaign against the military putsch with millions of mentions.

But around 10:00 pm local time (1530 GMT), they saw their Twitter acccess curtailed, with some saying it could not be used even with a VPN service.

Telenor, one of the country's main telecoms providers, confirmed authorities had ordered a blockade Friday to Twitter and Instagram "until further notice".

"Telenor Myanmar has challenged the necessity and proportionality of the directive... and highlighted the directive's contradiction with international human rights law," the company said in a statement.

The Norway-based group added it was "gravely concerned" and emphasised that access to communications services should be maintained at all times.

According to a document by the ministry seen by AFP but not verified, Twitter and Instagram were being used to "cause misunderstanding among the public".

NetBlocks, which monitors internet outages around the world, confirmed that other Facebook products -- like Whatsapp -- were facing disruptions.

Friday also saw around 200 teachers and students protest at a Myanmar university -- the largest show of public dissent within the country so far.

Displaying the three-finger salute borrowed from Thailand's democracy movements, the protesters sang a popular revolutionary song.

"We have to resist this dictatorship," lecturer Win Win Maw told AFP.

"If all civil servants participate in this movement, it's not easy to operate this government system."

Hours before the rally, Win Htein, a key aide of Suu Kyi, was arrested at his daughter's house, said Kyi Toe, press officer for her National League for Democracy party.

The 79-year-old NLD stalwart, considered Suu Kyi's right-hand man, has spent long stretches in detention for campaigning against military rule.

Speaking to local media ahead of his arrest, Win Htein called on people in the country to "oppose (the coup) as much as they can".

While Suu Kyi has not been seen in public since she was detained on Monday, Kyi Toe said she's currrently "under house arrest" in Naypyidaw, the country's capital, and was "in good health".

According to the Assistance Association for Political Prisoners (AAPP), a Yangon-based group that monitors political arrests in Myanmar, more than 130 officials and lawmakers have been detained.

'Hope broken'

With Facebook stifled on Wednesday, many people had moved to Twitter in recent days or started using VPN services to try to bypass the blockade.

After the Twitter restriction Friday, hashtags like #WeNeedDemocracy and #FreedomFromFear -- based on a famous quote by Suu Kyi -- started trending.

A so-called Civil Disobedience Movement has gathered pace online, calling on the public to voice opposition every night by banging pots and clanging cymbals to show their anger.

"I feel our hope is broken by the military after they seized power," said food vendor Thazin Oo, whose mobile phone case has a photo of Suu Kyi.

Police in Mandalay, Myanmar's second largest city, detained more than 20 people for banging pots and pans. They were sentenced Friday to seven days in prison for violating a public disorder law.

Another four university students from Mandalay were charged Friday for protesting at a small rally the day before without permission and breaking coronavirus rules.

As they were escorted from court in chains, they flashed a defiant three-finger salute to the waiting media.

In Naypyidaw, dozens of employees from several government ministries posed for group photographs wearing red ribbons and flashing the democracy symbol.

Some 300 MPs also held a virtual meeting Friday to convene an unofficial "parliament committee" in defiance of military rule, according to the NLD.

'Refrain from violence'

The coup has drawn condemnation globally.

On Thursday, US President Biden reiterated his call for the generals to reverse course.

"The Burmese military should relinquish power they have seized, release the advocates and activists and officials they have detained, lift the restrictions in telecommunications, and refrain from violence," he said.

His National Security Advisor Jake Sullivan also said the White House was "looking at specific targeted sanctions" on military-linked entities.

The UN Security Council took a softer line, voicing "deep concern" -- a step down from a draft Tuesday that had condemned the coup.

Diplomats said veto-wielding China and Russia, Myanmar's main supporters at the UN, had asked for more time Tuesday to finesse the council's response.

There have been calls on multinational companies working with Myanmar's military-linked businesses to cut ties as a way to pressure the generals.

Japanese beer giant Kirin -- long under scrutiny over its ties to Myanmar's army-owned breweries -- said Friday it was terminating a joint venture with a military-owned conglomerate.