NOUAKCHOTT (Reuters) - France backs efforts by West African states to boost security in their Sahel region, including a plan for a 5,000-strong multinational force to combat Islamist fighters, its foreign minister said on Thursday.

French Foreign Minister Jean-Marc Ayrault (L) and Mauritania's President Mohamed Ould Abdel Aziz meet in Nouakchott, Mauritania, April 6, 2017. REUTERS/John Irish

Jean-Marc Ayrault said the G5 Sahel states - Mali, Mauritania, Chad, Burkina Faso and Niger - must improve their counter-terrorism capacity.

“The countries of the G5 have decided to enter a new phase ... with the creation of a common force to protect their borders,” Ayrault said after meeting Mauritanian President Mohamed Ould Abdel Aziz.

“The second phase consists of training specialized troops, not to replace Barkhane, but to strengthen it in the fight against terrorist groups, but also all sorts of trafficking that is wreaking havoc on the region,” he told Reuters.

Former colonial power France intervened in 2013 to drive out al Qaeda-linked militants who seized northern Mali the year before. It has since deployed some 4,000 soldiers, known as the Barkhane force, across the region to hunt down Islamists.

U.N. peacekeepers have also been deployed to Mali.

The Sahel region, whose desert expanses stretch from Mauritania to Sudan, is home to several jihadist groups.

Mali-based groups have continued to launch attacks across the region in the past 18 months. A spike of violence in central Mali has spilled over its southern border into Burkina Faso.

A French soldier died in a clash with militants in Mali on Wednesday near the border with Burkina Faso in the latest example of risks faced by security forces.

Ayrault, on a two-day trip to the region with his German counterpart Sigmar Gabriel, will travel to Gao in Mali on Friday to pay tribute to the soldier.

Paris was already providing training and equipment and undertaking mixed patrols along border areas, Ayrault said, adding: “It will be a long-term project.”

A French diplomatic source said the aim was to create a 5,000-troop strong reaction force similar to the multinational contingent fighting Nigeria’s Boko Haram insurgency.

“The mission would cost several hundred million dollars as it would need to be properly equipped. It first needs to be rubber-stamped by the African Union and then the EU would be asked for financial aid,” the source said.