At least 50 people have been killed in central Myanmar in an air strike by the military on an event attended by opponents to its rule, according to media and members of a local resistance movement.

Citing residents in the Sagaing region, BBC Burmese, Radio Free Asia, and the Irrawaddy news portal reported between 50 and 100 people, including civilians, had died in the attack on Tuesday.

Reuters could not immediately verify the reports and a spokesperson for the ruling military did not answer a phone call seeking comment.

United Nations Secretary-General Antonio Guterres strongly condemned the attack and called for those responsible to be held accountable, his spokesman said, adding that Guterres “reiterates his call for the military to end the campaign of violence against the Myanmar population throughout the country”.

Myanmar has been in turmoil since a 2021 coup, with attacks by ethnic minority armies and resistance fighters challenging the rule of the military, which has responded with air strikes and heavy weapons, including in civilian areas.

A member of the local People’s Defence Force (PDF), an anti-junta militia, told Reuters fighter jets had fired on a ceremony held to open their local office.

“So far, the exact number of casualties is still unknown. We cannot retrieve all the bodies yet,” said the PDF member, who declined to be identified.

At least 1.2 million people have been displaced by post-coup fighting, according to the UN.

Tuesday’s incident could be one of the deadliest among a string of air strikes since a jet attacked a concert in October, killing at least 50 civilians, local singers and members of an armed ethnic minority group in Kachin State.

Myanmar’s pro-democracy government-in-exile, the National Unity Government, condemned the attack, calling it “yet another example of (the military’s) indiscriminate use of extreme force against civilians”.

Last month, at least eight civilians including children were killed in an air strike on a village in northwest Myanmar, according to a human rights group, ethnic minority rebels and media.

The military has denied international allegations it has committed atrocities against civilians and says it is fighting “terrorists” determined to destabilise the country.

Western countries have imposed sanctions on the junta and its vast business network to try to choke off its revenue and access to arms from key suppliers like Russia. 

By Kanupriya Kapoor in NAYPYIDAW