Three Malian troops were killed and five wounded by a roadside bomb in the centre of the country Thursday, military sources said, in the latest attack in the Sahel state.

The three -- members of the National Guard, a unit of the Malian armed forces -- had been travelling between Koro and Mondoro, near the border with Burkina Faso, two sources said, speaking on condition of anonymity.

They added that five other guardsmen were also injured in the attack. A doctor, who requested anonymity, said that one is in critical condition.

Mali has been struggling with a jihadist insurgency that broke out in the north of the country in 2012 before spreading to the centre and then to Burkina Faso and Niger, often inflaming ethnic rivalries.

On Friday, the UN's High Commissioner for Refugees (UNHCR) said that more than two million people in the Sahel had fled their homes due to violence.

Laying roadside bombs -- or improvised explosive devices (IED) -- is a tactic commonly used by jihadist groups in the region, to deadly effect.

France, which has 5,100 troops deployed across the Sahel, has lost five soldiers since late December to IEDs, for example.

The makeshift bombs have also killed 60 UN peacekeepers in Mali.

The 13,000-strong MINUSMA peacekeeping force has suffered 146 hostile deaths since it was first established in 2013.

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