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.

The US 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 dialog 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.