* Malian army clashes with Islamists

* Dozens killed, 20 soldiers missing - military source

By Tiemoko Diallo BAMAKO, July 6 (Reuters) - Mali's army and suspected al Qaeda militants fought two gun battles over the weekend that killed dozens and left about 20 soldiers missing in a remote desert region, military sources said.

A Malian military patrol clashed with militants near Tessalit, in Mali's north, on Friday and were ambushed early Saturday morning. Mali's army confirmed firefights took place but gave no details.

The violence is the latest in a series of incidents in the vast desert region which has long hosted rebels and smugglers and now increasingly is being used by militants known as al Qaeda in the Islamic Maghreb (AQIM).

"The army fought very deadly clashes with Islamists on July 3 and 4 northeast of (the northern town of) Timbuktu. After very heavy fighting, there were losses on both sides," the army said late on Sunday. The statement gave no details on the death toll.

A military source said dozens had died in the two attacks and an army colonel was amongst the estimated 20 soldiers who went missing.

"We don't know if he is dead or has been taken hostage," the source, who asked not to be named, told Reuters.

The fighting is the third such incident since Mali's security forces stepped up operations against AQIM, which last month killed a British hostage.

AQIM is the North African wing of the global militant franchise but the killing of a Briton, who was amongst a group of tourists seized in January, was the the first time they had carried out threats to execute hostages.

Although the killing has intensified the focus on AQIM, the group's activities are based as much on a complex mix of criminality and opportunism stemming from smuggling and hostage-taking as they are on hard-line Islamism. (Editing by David Lewis and Jason Neely)

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