BAMAKO – Malian security forces have clashed with a group of suspected al Qaeda militants in the northern Tessalit region, killing several people, a senior military source in the West African country said Wednesday.

The armed forces sent out patrols to try to track down the suspected militants around Mali's northern border region with Algeria, deep in the Sahara, after the assassination this month of the security chief of the Timbuktu region, the source said.

One of the patrols came across a group of gunmen in several armed 4x4s in the Timetrine sector of Tessalit, the source, a senior military official close to the Malian defense ministry, told Reuters on condition of anonymity.

There was a chase and the group took refuge in some hills. There was cross-fire. There is no exact toll at the moment but there are several dead on both sides, the source said.

The vast swathes of poorly-policed and largely empty desert in northern Mali, Niger and Mauritania have increasingly been used as recruitment and training grounds by Islamist militants from Algeria in recent years.

One of the groups -- al Qaeda in the Islamic Maghreb (AQIM), the North African wing of the global militant franchise -- said two weeks ago it had carried out its threat to kill a British hostage it was holding in the Sahara.

The AQIM title was adopted when rebels with Algeria's Salafist Group for Preaching and Combat (GSPC) affiliated themselves to the al Qaeda network.

The GSPC had largely been waging a campaign of bombings and shootings along Algeria's Mediterranean coast but a security crackdown reduced its ability to mount attacks there, forcing it south into the largely ungoverned reaches of the Sahara.

Mali, Niger and Mauritania as well as Algeria have come under pressure from the United States and Europe to tackle Islamist militant violence.

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(Writing by Nick Tattersall)