Five people including a relief worker were wounded in an attack on a local aid organisation's vehicle in conflict-torn northeastern Myanmar, the group said Sunday, the second such attack within a week.

The vehicle carrying 13 people, mostly civilians and national journalists, was attacked Saturday afternoon as it travelled from Laukkai, a town in the northern state of Shan bordering China where battles between ethnic Kokang rebels and the Myanmar army have raged for nearly two weeks.

A "Myanmar Red Cross volunteer, a journalist and three civilians" were wounded in the attack, the Myanmar Red Cross Society said in a statement.

The incident came only four days after an attack on a convoy led by the Myanmar Red Cross, which left two aid workers wounded and forced local relief groups to suspend work in the region that tens of thousands have fled since the clashes erupted.

The Myanmar Red Cross is separate from the better-known International Committee of the Red Cross.

"I thought I was going to die," one of the journalists in the vehicle that came under fire Saturday told AFP, asking to remain anonymous.

"They fired continuously for half an hour," he said, adding the Red Cross-flagged vehicle appeared to have been "targeted" before the group were rescued by the Myanmar army.

Htun Myat Lin, spokesman for the Myanmar Nationalities Democratic Alliance Army (MNDAA), the main Kokang rebel group, denied his organisation was behind the attack, and said the army was trying to "flare up" tensions between rebels and civilians.

- Surprise attacks -

Fighting has raged in the remote and rugged region after a series of surprise attacks launched on February 9 by the Kokang rebels.

It is the first major unrest in the region since 2009 and has renewed doubts over Myanmar's attempt to forge a nationwide ceasefire in the former junta-ruled nation that is still wracked by ethnic insurgencies.

In another ominous sign for peace, the Kokang have in recent days been joined in their fight with Myanmar's army by other nearby rebel groups, including the Ta'ang National Liberation Army and the powerful Kachin Independence Army.

The MNDAA spokesman meanwhile reported heavy airstrikes and at least four helicopters circling the area, saying government forces had used "a lot of artillery" in recent days.

Fears are increasing for the safety of civilians still trapped in the Kokang region -- it is unclear how many remain given the limited access available to aid groups and there are no official figures on the civilian death toll.

Tun Tun Oo, head of an organisation linked to the Myanmar Red Cross in Shan state's largest town Lashio, told AFP his team had been planning a mission to areas including Laukkai on Monday but would now postpone operations.

At least 30,000 civilians have fled across the border into southwestern China, while tens of thousands more are believed to have been displaced on the Myanmar side of the border.

Myanmar has declared a state of emergency in the region in response to the conflict, which has also sparked alarm in Beijing.

Chinese officials have stepped up border controls and called on all parties to prevent a further escalation of fighting.