The group of nine vehicles was approaching Ommati village in northern Shan State on Tuesday night, and failed to stop when signalled by soldiers, junta spokesman Zaw Min Tun said.

"From a distance of around 200 metres, security forces used a light to try to halt them but they did not stop. The security forces fired three gunshots aiming at the sky," Zaw Min Tun said in a statement to state media.

International aid and rescue workers have been coming in to Myanmar, including from its close ally and neighbour China, since Friday's 7.7-magnitude quake, which has killed more than 2,800 people and left thousands homeless.

But access to the worst-hit areas has been hindered by wrecked roads, poor telecommunications and ongoing violence between the junta and pro-democracy militias.

Zaw Min Tun said the convoy belonged to the Chinese Red Cross and that the junta was investigating the incident.

He said the convoy involved had given "no advance notification to Myanmar, or a respective embassy, or office of the military attache," he said.

Shan state has been the scene of intense fighting between the junta and ethnic minority armed groups which have seized control of large areas of territory.

The junta and the TNLA -- a major ethnic minority armed group -- have been clashing near Ommati village, Zaw Min Tun said, adding that "there are some groups taking political advantage (of rescue missions)".

When asked to comment on the incident, China's foreign ministry told reporters that equipment sent by China's Red Cross had arrived and that the team and supplies were "safe at present".

"We urge all parties in Myanmar to provide unhindered channel for aid," it said on Wednesday.