Eleven anti-coup protesters have been killed across Myanmar as protesters returned to the streets after the deadliest day since the military seized power from civilian leader Aung San Suu Kyi.

At least 44 protesters died yesterday as security forces cracked down on pro-democracy demonstrations, taking the death toll since last month's coup to more than 120, according to the Assistance Association for Political Prisoners (AAPP) monitoring group.

Those killed today were shot dead in several locations in the country's central regions, and witnesses said the junta was again using lethal force against protesters.

"Two men were killed because of gunshots and six others were injured," a witness in Magway region's Aunglan town said, adding that one of the dead was shot in the chest.

"He was right besides me. Another one got shot in his head."

Six fatalities were also reported in the city of Myingyan. Among those dead were "three people, including a woman with gunshots," said a resident.

There was a further death in the city of Monywa, state media said, while two men in their 20s were killed in Mandalay, according to a local doctor and a reporter.

The country has been in uproar since the coup on 1 February, with daily protests demanding a restoration of democracy despite the junta's increasingly forceful attempts to quell dissent.

News of the violence came out in the afternoon due to a block on mobile data networks across Myanmar - which also scuppered a scheduled court appearance by Ms Suu Kyi.

The video hearing for the Nobel laureate - who spent more than 15 years under house arrest during previous military rule - was scheduled for Myanmar's capital Naypyidaw, but it was postponed until 24 March, according to her lawyer Khin Maung Zaw.

"There's no court hearing because there's no internet and the hearing is conducted by video conference. We cannot do video," he said.

United Nations Secretary-General Antonio Guterres has said he is appalled by the escalating violence in Myanmar "at the hands of the country's military," U.N. spokesman Stephane Dujarric  said.

"The Secretary-General urges the international community to work collectively and bilaterally to help bring an end to the repression by the military," Mr Dujarric said in a statement.

Aung San Suu Kyi faces at least four charges

Myanmar authorities have cut off the internet every night for several weeks, normally restoring services in the morning, but monitoring service Netblocks said mobile data networks were kept offline today.

Ms Suu Kyi faces at least four charges.

Military authorities have also accused her of accepting illegal payments - allegations her lawyer says are "groundless".

Ms Suu Kyi's postponed hearing came a day after violent clashes between security forces and protesters, which also saw the torching of several Chinese-owned factories in a textile-producing district of commercial hub Yangon as many protesters believe Beijing is supportive of the coup.

Six Yangon townships were under martial law by morning - anyone arrested there faces trial by military tribunal rather than civilian courts, with sentences ranging from three years' hard labour to execution.

Chinese foreign ministry spokesman Zhao Lijian described the incidents as "nasty".

China "is very concerned about the impact on the safety of Chinese institutions and personnel," he told reporters in Beijing, adding the Myanmar security forces had reinforced the area around the factories.

"China will continue to urge Myanmar to take concrete steps to stop all acts of violence and bring the perpetrators to justice and ensure the safety of Chinese people's life and property."

Taiwan, meanwhile, advised its companies in Myanmar to fly the island's flag to avoid being targeted.

State-run television confirmed today that a police officer was shot dead in the city of Bago, northeast of Yangon, during a protest.

International alarm over the bloodshed is growing, but so far Myanmar's generals have shown no signs of heeding calls for restraint.

Tom Andrews, United Nations special rapporteur on rights in Myanmar, tweeted that he was "heartbroken/outraged" at yesterday's events and appealed to UN member states to act.

"Junta leaders don't belong in power, they belong behind bars," he wrote.

"Their supply of cash & weapons must be cut now."

UN envoy for Myanmar Christine Schraner Burgener also condemned the bloodshed, while the UK - the country's former colonial ruler - said it was "appalled" by the use of force "against innocent people".

Last week, Mr Andrews said there was growing evidence that the junta was committing crimes against humanity - including murder, forced disappearances and torture.

Amnesty International has also accused the Myanmar military of premeditated killings and using battlefield weapons on unarmed protesters.