At least four United Nations peacekeepers were killed by a roadside bomb in central Mali on Wednesday, the U.N. said.

A U.N. vehicle was blown up when a mine or explosive device detonated in Mopti region on Wednesday afternoon, the U.N. mission in Mali, MINUSMA, said in a statement. Four other peacekeepers were seriously injured, with medical evacuation under way, the statement read.

"MINUSMA is currently strengthening its security system in central Mali. Forced into a corner, terrorists multiply their attacks," said MINUSMA chief Mahamat Saleh Annadif.

"These acts reflect their distress and in no way detract from MINUSMA's determination to carry out its mandate," Annadif added.Earlier Wednesday, Mali's army said six of its soldiers were killed in a similar incident a day before in the central Segou region.

The army vehicle drove over a roadside bomb on Tuesday near the town of Dioura, said army spokesman Nouhoum Samake, without providing further details.

The West African country has been volatile since separatist rebel groups, and later al-Qaeda-associated militants, took control of the northern region in the wake of a 2012 military coup.

French and African military operations, alongside the Malian army, scattered militants and restored government control over the area, but rebel activities and military operations continue in some regions, despite the signing of various peace agreements.

The United Nations has stationed almost 15,000 peacekeepers in Mali to stabilize the country.