Seven people were killed in a gun battle between border guards and Chinese illegal migrants at a remote frontier crossing in northeast Vietnam, authorities said Friday.

Sixteen Chinese nationals -- 10 men, four women and two children -- were detained early Friday after attempting to enter Vietnam, the Quang Ninh provincial government said in a statement.

While authorities were preparing to send them back, "some Chinese men in this group seized guns from Vietnamese border guards and shot at them... killing one guard on the spot," the statement said.

Vietnamese and Chinese authorities sought to calm the situation but the migrants refused to drop their weapons and a firefight erupted, it added.

In total two Vietnamese border guards and five Chinese migrants were killed, according to the statement, which said the incident was "not a terrorist attack".

It was not immediately possible to verify the authorities' account.

The statement did not say whether the dead included Chinese women and children.

Vietnamese state media reported that the Chinese migrants were from the Muslim-majority province of Xingjian but there was no independent confirmation.

Vietnam's remote northeastern region, which borders China's Guangxi province, is poor and mostly populated by a patchwork of ethnic minority groups.

There have been previous human trafficking and people smuggling cases in the area, including of Vietnamese women forced to marry Chinese men and young boys kidnapped for sale to wealthy childless Chinese families.

But it is unusual for irregular Chinese migrants to be caught trying to enter Vietnam, with more Vietnamese migrants travelling north to find work in China's fast-growing cities.

No data exists on the scale of economic migration across the remote, sparsely guarded border but it is believed to be widespread as it is difficult for the neighbouring communist countries to control all movement across their 1,300 plus kilometre-long joint border.