YANGON: Myanmar activists held protests across the country overnight two months after the military seized power, as a United Nations special envoy warned that "a bloodbath is imminent" because of the intensified crackdown on anti-coup demonstrations.

The envoy's warning follows a flare-up in fighting between the army and ethnic minority insurgents in frontier regions.

At least 20 soldiers were killed and four military trucks destroyed in clashes with the Kachin Independence Army (KIA), one of Myanmar's most powerful rebel groups, DVB news reported.

A KIA soldier cited by Kachin Liberation Media said the attack happened on Wednesday afternoon.

Reuters could not immediately verify the reports and a junta spokesman did not answers calls seeking comment.

Myanmar military aircraft have started bombing positions of another group, the Karen National Union (KNU), for the first time in more than 20 years and thousands of villagers have fled from their homes, many into Thailand.

Myanmar has been rocked by almost daily protests since the army overthrew Aung San Suu Kyi’s elected government on Feb. 1 citing unsubstantiated claims of fraud in a November election. Suu Kyi and other members of her National League for Democracy (NLD) are being held in detention

In cities across Myanmar there were further candle-lit protests overnight including in Myitnge in the Mandalay region, according to media and photographs on social media.

SUU KYI DUE IN COURT

The junta has accused Suu Kyi of several minor crimes but could soon charge her with treason which can be punishable by death, Khit Thit Media reported on Wednesday.

Reuters could not confirm this, but the next hearing in her case is due later on Thursday.

Suu Kyi and one of her lawyers, Min Min Soe, held their first video conference since her arrest on Wednesday.

"Amay looks healthy, her complexion is good," Min Min Soe said by telephone, using an affectionate term meaning "mother" to refer to her.

Ousted members of parliament, mostly from Suu Kyi's party, vowed to set up a federal democracy in a bid to address a long-standing demand from ethnic minority groups for autonomy.

The military rejects such proposals and sees itself as the only institution capable of holding the country together.

The lawmakers who have set up a parallel civilian government, the Committee for Representing Pyidaungsu Hluttaw (CRPH), also announced the abolishment of a 2008 constitution set up by the military that guarantees the army's influence.

"The new day begin here!" Dr Sasa, the international envoy of the CRPH, said on Twitter, referring to what for now is a largely symbolic move.

U.S. URGES CHINA TO USE INFLUENCE

The U.N. special envoy on Myanmar Christine Schraner Burgene told the 15-member U.N. Security Council that the military was not capable of managing the country, and warned the situation on the ground would only worsen, according to comments shared with reporters.

The council must consider "potentially significant action" to reverse the course of events as "a bloodbath is imminent," Schraner Burgener said.

The council's statements have so far expressed concern and condemned violence against protesters, but dropped language calling the takeover a coup and threatening possible further action due to opposition by China, Russia, India and Vietnam.

At least 536 civilians have been killed in protests, 141 of them on Saturday, the bloodiest day of the unrest, according to the Assistance Association for Political Prisoners (AAPP).

The United States on Wednesday urged China, which it has significant economic and strategic interests in Myanmar, to use its influence to hold account those responsible for the military coup.

While Western countries have strongly condemned the coup, China has been more cautious and the government's top diplomat Wang Yi called for stability during a meeting with his Singaporean counterpart Vivian Balakrishnan on Wednesday.

"China welcomes and supports ASEAN's adherence to the principle of non-interference ... and the 'ASEAN approach' in playing a positive role in promoting the stability of the situation in Myanmar," China's foreign ministry said in a statement after the meeting, referring to the Association of Southeast Asian Nations.

Singapore's foreign ministry said the ministers "called for a de-escalation of the situation, a cessation of violence and the commencement of constructive dialogue among all sides".

ASEAN, of which Myanmar is a member, has a pledge not to interfere in each other's affairs, but led by Indonesia some countries have been actively pushing diplomatic efforts to defuse the crisis.

Still, the military has up to now appeared impervious to outside pressure.