The governor of the flashpoint Malian town of Kidal returned to his city on Thursday after more than a yearlong absence but left after a brief visit, as the country prepares for crucial nationwide elections later this month, security sources said..

"The governor of Kidal, who arrived today, left late afternoon by the plane that brought him" from Bamako, a Malian military source said without explaining the "strategic reasons" for his departure.

The departure back to Bamako of the governor, Adama Kamissoko, was confirmed by a source in the UN's African force in Mali, who said that when he arrived in Kidal there was "really some tension."

Questioned shortly after his arrival, Kamissoko said that the buildings of the governor's administration were "occupied by armed groups" which he did not name. He did not rule out returning to Bamako "before coming back", he said.

His visit comes at a time of violent protests in the northeastern rebel stronghold.

Although Tuareg separatists have allowed the Malian army to enter Kidal as part of a peace deal ahead of the July 28 vote, the situation on the ground is increasingly tense.

Earlier Kamissoko told AFP before boarding a flight at Bamako airport: "I am happy to be back in my post."

"The priority now is obviously organising the presidential election. I hope everything goes well," he said, flanked by regional government officials.

Local government has been absent from Kidal for more than a year since the National Movement for the Liberation of Azawad (MNLA) and allied armed factions linked to Al Qaeda seized Mali's vast desert in the north.

Last week, some 200 Malian soldiers entered Kidal to try and improve security.

However, in recent days, supporters and opponents of the Malian army have staged daily demonstrations.

At least two UN peacekeepers and a French soldier were injured by stones thrown during a violent demonstration over the weekend.

Two Malian civilians were seriously wounded by gunfire, although the circumstances behind the shootings remain unclear.

The occupation of Kidal by the MNLA has been a major obstacle to organising the election, seen as crucial to reuniting deeply-divided Mali after an 18-month political crisis.

Malian military officers staged a coup in March last year after being overpowered by an MNLA rebellion that seized key northern cities before being sidelined by its Islamist allies.

A French-led intervention launched in January drove out the Islamists but the MNLA took control of Kidal, 1,500 kilometres (930 miles) from the capital, which they consider the heart of the desert territory they call Azawad.

There is widespread scepticism about Mali's ability to stage elections, with the task of distributing more than seven million polling cards in a country where 500,000 people have been displaced viewed by many as an impossibility.