The World Health Organization is coordinating its earthquake response from its Geneva headquarters "because we see this as a huge event" with "clearly a very, very big threat to life and health", spokeswoman Margaret Harris told a media briefing.

"We've activated our logistics hub to look particularly for trauma supplies and things like external fixators because we expect that there will be many, many injuries that need to be dealt with," Harris said.

She said the WHO would also be concentrating on getting in essential medicines, while the health infrastructure in Myanmar itself might be damaged.

Harris said that due to recent experience with the 2023 Turkey-Syria earthquakes, "we know very well what you need to send in first".

The UN health agency already has a special cell to deal with Myanmar, which has been rocked by fighting between numerous ethnic rebel groups and the army.

And by chance, the WHO had done an assessment in recent weeks of the best ways to get supplies into Myanmar.

"We are ready to move in -- but now we have to know exactly where, what and why. It's information from the ground that's really critical right now," said Harris.

Meanwhile the medical charity Doctors Without Borders (MSF) called for rapid access to affected areas and the timely approval of supplies and personnel.

"MSF medical and humanitarian staff in Myanmar and neighbouring countries are ready to respond at scale to the urgent needs of affected communities, once authorities facilitate swift and unhindered access for teams to do assessments and provide medical care," it said in a statement.

"The ability to deploy assessment teams -- and ideally, surgical teams -- is crucial in the first hours and days after an earthquake to deliver life-saving surgical care for the injured."

The Geneva-based organisation said that given the 7.7 magnitude of the quake, its impact on people "could be devastating", particularly for those needing immediate help for trauma injuries.