Rebel fighters in Mali have captured at least 12 government soldiers along with their vehicle and equipment, reports say.

The incident on Monday took place during a government patrol outside the town of Kona and near the city of Mopti, as fears rise that the rebels, who seized vast swathes of Mali's north, are moving increasingly closer to areas under government control.

Earlier on Monday, government soldiers fired on the al-Qaeda linked group, Ansar Dine, 60km east of Mopti.

Heavily armed Islamist groups in convoys of pick-up trucks had been reported in the Mopti region, where government troops have been stationed since the revolt, a Malian military official told the Reuters news agency.

"The rebels have been advancing and have been sighted in several places ... We are waiting for them. If they attack us,
we will fight back," said the official, who asked not to be identified.

A military official, who spoke on condition of anonymity because he was not authorised to speak to the media, said the rebels had reached the village of Bourei, only 40km from the last town under the purview of Mali's military.

An employee of a bus company called Binke Transport also confirmed that the rebels had arrived in the village.

"There are numerous Islamists in Bourei aboard all-terrain vehicles and even armored vehicles that they have stolen from the Malian military,'' Mamadou Guindo told The Associated Press.

Rising tensions

"There is a real tension there, and we are considering stopping bus transport between Gao and Sevare (towns) for the security of our passengers.''

Mali's government lost control of the northern half of the country - an area the size of France - in April after the rebels took advantage of a power vacuum following a March coup that overthrew the democratically elected president.

A group called Ansar Dine has been implementing its strict version of Islamic law in the north, carrying out public executions, amputations and whippings.

An Ansar Dine spokesman declined to comment on the reports on Monday of a stepped-up rebel presence closer to the line of government control.

The UN Security Council has authorised military action to wrest the north back, but says there must first be political progress made following the military coup last year.