Four UN peacekeepers have been killed and four more were wounded after their vehicle hit an explosive device in Mali's central Mopti region.

The UN's mission in Mali, MUNISMA, said the vehicle transporting the blue helmets struck an improvised explosive device on Wednesday. The medical evacuation of the four "seriously injured" peacekeepers was under way, a statement said.

The incident happened a day after six Malian soldiers were killed in another blast.

"MINUSMA is currently upgrading its security presence in central Mali," mission chief Mahamat Saleh Annadif said. "Cornered, the terrorists are multiplying their attacks of unspeakable vileness."

The UN mission in Mali, which has more than 11,000 troops and was established in 2013, is one of the most dangerous peacekeeping operations in the world, with troops and convoys regularly coming under attack from armed groups.

According to UN figures, more than 146 members of the mission have been killed since 2013.

The security situation in Mali has been fragile since 2012 after armed groups captured the entire northern part of the country and were only pushed back a year later following a military intervention by France.