Baba Ould Cheikh, the mayor of Tarkint in the Gao region, was snatched by six armed men between January 21 and 23, a member of his family told AFP, underlining increasing insecurity months ahead of a presidential election.

Cheikh had negotiated the release of Europeans kidnapped by jihadists in the past, and is the latest victim of either criminal elements or jihadists who frequently organise such kidnappings.

"There is no doubt he was taken away. He didn't just disappear. Either the kidnapping was done by people he had a disagreement with, or Islamists who organised it," the security source said.

The mayor was named in an enquiry into a drug smuggling operation in 2009 involving a Boeing 727 flown from Venezuela and burnt after unloading the cargo in the Gao region, according to the UN drugs agency.

He was arrested for cocaine trafficking in April 2013 but released months later due to lack of evidence.

Meanwhile, the powerful Group for Support of Islam and Muslims (JNIM in its Arabic acronym) claimed two attacks against the Malian army last week that left 18 soldiers dead.

The Mauritanian news agency Al-Akhbar, which regularly reports claims of responsibility from jihadists in the Sahel, published a statement from the Islamist militant coalition which stated it lost four men in the attacks.

Islamist extremists linked to Al-Qaeda took control of the desert north of the former French colony in early 2012, but were largely driven out in an ongoing French-led military operation launched in January 2013.

In June 2015, Mali's government signed a peace agreement with coalitions of non-jihadist armed groups. But Islamist insurgents remain active, and large tracts of the country are lawless.