YANGON (REUTERS) - Myanmar security forces opened fire on Monday (Jan 15) to disperse protesters in the city of Mandalay, the media outlet Frontier Myanmar reported.

The number of casualties was not clear, it said. A member of a student union in the city said some people were wounded.

Myanmar's ousted leader, Ms Aung San Suu Kyi, has been remanded in custody until Wednesday, not Monday as previously thought, her lawyer told media, as protesters began gathering again to demand her release and an end to military rule.

Security forces in Myanmar deployed armoured vehicles in major cities two weeks after the military overthrew Ms Suu Kyi's government and detained her on charges of illegally importing six walkie-talkie radios.

Her detention was due to expire on Monday but her lawyer, Mr Khin Maung Zaw, told media a judge at a court in the capital, Naypyitaw, had said she was remanded until Feb 17.

"Whether it is fair or not, you can decide yourself," he said. A member of the lawyer's team said the judge had spoken to Ms Suu Kyi via video conferencing and she had asked if she could hire a lawyer.

The Feb 1 coup and the arrest of Ms Suu Kyi and others have sparked the biggest protests in Myanmar in more than a decade. Hundreds of thousands have taken to the streets across the country for 10 days to denounce the coup, which derailed the South-east Asian country's tentative transition to democracy, and to call for Ms Suu Kyi's release.

The unrest has revived memories of bloody outbreaks of opposition to almost half a century of direct army rule, which ended when the military began a process of withdrawing from civilian politics in 2011.

Violence this time has been limited but on Sunday, police opened fire to disperse protesters at a power plant in northern Myanmar although it was unclear if they were using rubber bullets or live rounds and there was no word on casualties.

As well as the demonstrations around the country, the military is facing a strike by government workers, part of a civil disobedience movement that is crippling many functions of government.

More than a dozen police trucks with four water cannon vehicles were deployed on Monday near the Sule Pagoda in central Yangon, which has been one of the main demonstration sites in the commercial capital, as groups of protesters began gathering peacefully outside the central bank and the Chinese embassy.

At the bank, several hundred protesters held up signs calling for colleagues to join the CDM - the civil disobedience movement - and stating their refusal to accept the coup. An armoured vehicle and about six trucks carrying soldiers were parked nearby, a witness said.

Armoured vehicles were also deployed on Sunday in the northern town of Myitkyina and Sittwe in the west, the first large-scale use of such vehicles since the coup.

Police in Naypyitaw detained about 20 high-school students protesting by a road. Images posted on social media by one of the students showed them chanting slogans of defiance as they were taken away in a police bus.

"Remember, we don't swear at the police and don't sign anything at the police station," one student can be heard saying.

Media also showed orderly ranks of protesters marching in Naypyitaw with pictures of Ms Suu Kyi with the message: "We want our leader."

Ms Suu Kyi, 75, spent nearly 15 years under house arrest for her efforts to end military rule.

The judge in Naypyitaw had spoken to Ms Suu Kyi by video conferencing and she had asked if she could hire a lawyer, Mr Khin Maung Zaw told Reuters.

The government and army could not be reached for comment. Residents reported an Internet outage after midnight on Sunday which lasted until about 9am.

'Desperation'

The army has been carrying out nightly arrests and last Saturday gave itself sweeping search and detention powers. At least 400 people have been detained since the coup, the monitoring group Assistance Association for Political Prisoners said.

On Sunday, the military published penal code amendments aimed at stifling dissent.

"It's as if the generals have declared war on the people," UN Special Rapporteur Tom Andrews said on Twitter.

"Late night raids, mounting arrests, more rights stripped away, another Internet shutdown, military convoys entering communities. These are signs of desperation. Attention generals: You WILL be held accountable."

Ms Suu Kyi's party won a 2015 election and another on Nov 8 but the military said the vote was marred by fraud and used that complaint to justify their coup. The electoral commission dismissed accusations of fraud.

Western embassies - from the European Union, Britain, Canada and 11 other nations - issued a statement late on Sunday calling on security forces to "refrain from violence against demonstrators and civilians, who are protesting the overthrow of their legitimate government".

The amendments to the penal code set out a 20-year prison term for inciting hatred of the government or military or hindering the security forces engaged in preserving state stability.

Hindering the security forces carrying out their duties is punishable by seven years in prison while spreading fear, fake news or agitating against government employees gets three years, according to the amendments posted on a military website.

The junta has ordered civil servants back to work, threatening action.

In the latest sign of disruption by workers, the Department of Civil Aviation said in a statement many staff had stopped coming to work since Feb 8, causing flight delays.

Some trains have also stopped running, media reported.