THE lawyer for Myanmar's elected leader Aung San Suu Kyi and ousted President Win Myint said they were being held in their homes after being detained on Monday when the army seized power and that he was unable to meet them.

Lawyer Khin Maung Zaw said he was seeking their unconditional release but had been told they were still under investigation.

Teachers and students in Myanmar earlier rallied to a growing civil disobedience campaign as the anti-coup protest movement won the support of Suu Kyi's political party.

The Nobel Peace laureate, 75, has not been seen since her arrest on Monday. Police have filed charges against her for illegally importing and using six walkie-talkie radios found at her home.

"We expect justice from the judge, but it is not certain. We hope for the best, but prepare for the worst. Of course, we want unconditional release as they have not broken the law," her lawyer told reporters in the capital, Naypyidaw.

Stepping up measures to quell discontent, police arrested one of Suu Kyi's veteran aides and dozens of people who had joined noisy demonstrations against Monday's coup.

International pressure on the junta increased with the U.N. Security Council urging the release of detainees and Washington considering sanctions on the ruling generals.

U.N. Myanmar envoy Christine Schraner Burgener strongly condemned the military's actions in a call with the country's deputy military chief Soe Win and called for the immediate release of all those detained, a U.N. spokesman said on Friday.

Two days after a temporary ban on Facebook., authorities ordered internet providers to block Twitter and Instagram, said Norway's Telenor Asa [TEL.OL]. Twitter user numbers had jumped after the ban on Facebook.

Teachers became the latest group to join a civil disobedience campaign with some lecturers refusing to work or cooperate with authorities over the coup that halted a long and unsteady transition to democracy.

"We want the military coup to fail," said lecturer Nwe Thazin Hlaing at the Yangon University of Education.

Reuters was unable to reach the government for comment.

The disobedience campaign, which began with doctors, has also spread to some government offices and on Friday won the formal backing of Suu Kyi's National League for Democracy (NLD).

In a statement, the party denounced the coup and Suu Kyi's detention as "unacceptable" and said it would help people who are arrested or sacked for opposing the takeover.

Army chief Min Aung Hlaing took power saying there were irregularities in an election last November, which the NLD won in a landslide. The electoral commission has said the vote was fair.

There has been no outpouring of people onto the streets in a country with a bloody history of crackdowns on protests, but there were signs of coup opponents growing bolder - with dozens of youths parading in the southeastern city of Dawei.

COLOUR RED

In the biggest city, Yangon, supporters hung red clothing, ribbons and balloons outside their homes to show support for Suu Kyi.

"I hung my red dress outside the shop since yesterday to show our support for Mother Suu," said Cho Cho, 39, a salad shop owner. "This is our last fight for democracy: The fight for our children."

But authorities also began to step up action against coup opponents.

In Myanmar's second city of Mandalay, 30 people were arrested over pot-banging protests which have taken place for the last three nights.

Eleven Media quoted Maung Maung Aye, deputy head of the regional police force, as saying they were accused of breaking a law against "causing noise in public streets".

The latest high-profile detainee was 79-year-old Win Htein, a stalwart of Suu Kyi who was repeatedly imprisoned during their decades of struggling against previous juntas.

"I have never been scared of them because I have done nothing wrong my entire life," he told Reuters by phone as he was taken away.

Reuters was unable to reach police for comment on his arrest or what charges could be brought against him.

The 15-member U.N. Security Council in a statement on Thursday called for the release of all detainees and for respect for human rights, fundamental freedoms and the rule of law.

But before it won consensus among members that include China and Russia, which have close ties to Myanmar's army, the language of the draft was changed to remove any mention of a coup.

CREDIBLE ELECTION

U.S. Secretary of State Antony Blinken will discuss Myanmar in a Friday online meeting with his British, French and German counterparts, a U.S. official said.

National security adviser Jake Sullivan said on Thursday targeted sanctions on individuals and on entities controlled by the military were under consideration.

He spoke by phone with ambassadors from the Association of South East Asian Nations (ASEAN) regional bloc. Indonesia and Malaysia later said regional foreign ministers would be asked to hold a special meeting on the situation.

Myanmar's generals have few overseas interests that could be targeted by sanctions, but the military has extensive business interests that could suffer if foreign partners leave.

Japanese drinks company Kirin Holdings said on Friday it was terminating its alliance with a top Myanmar conglomerate whose owners, according to the United Nations, include members of the military. Kirin said the coup had "shaken the very foundation of the partnership".