Heavy gunfire in northern Mali town of Gao

Malian troops and suspected Islamist militants are exchanging heavy gunfire on the streets of Gao in northern Mali.

A BBC correspondent in the town says the clashes began near the central police station but have since spread.

It comes a day after a suicide bomber blew himself up near a checkpoint at a northern entrance to the town - the second such attack in two days, BBC reports.

Gao was retaken just over two weeks ago by French and Malian forces, who supposedly drove out the Islamists.

Security had been tightened in the wake of the suicide attacks, with military patrols stepped up and checkpoints put in place.

The Movement for Oneness and Jihad in West Africa (Mujao) said it had carried out Sunday's attack on Malian troops as well as both the suicide bombings, AFP news agency reports.

On Saturday, Mujao spokesman Abou Walid Sahraoui said: "We are dedicating ourselves to carrying out more attacks against France and its allies."

However, worries that Islamist militants had infiltrated Gao seems to have become reality, as they are waging a guerrilla war in the town, he adds.

There was no immediate comment from the Malian and French militaries.