The European Union is facing a dilemma over its remaining presence in Mali and the wider West African Sahel region, since it does not want to cooperate with Russia's expanding military forces, its top diplomat said on Wednesday.

The decision by junta-led Mali, Burkina Faso and Niger to withdraw from West African bloc ECOWAS has further complicated EU presence in the region, the bloc's foreign policy chief Josep Borrell said ahead of a defence ministers meeting in Brussels.

"It is very significant that these three states, all of them with military dictatorships, decided to leave the regional body ... at the same time that we see the Russian influence increase," Borrell said.

"This creates a new geopolitical configuration of this area."

He added that Russia's presence was already strong in Mali and could be soon in Niger and Burkina Faso. The EU has until May 24 to decide whether or not to stay in Mali, Borrell said.

"We still have a couple of missions in Mali that have not been withdrawn, but... we don't want to cooperate with Africa Corps," he added.

Africa Corps is the name of the Russian military presence that has succeeded Wagner group, the mercenary force that deployed to Mali in 2021. Last week a contingent flew to Burkina Faso.

The democratic governments of Mali, Burkina Faso and Niger were all overthrown in military coups since 2020. All face an Islamist insurgency that has killed thousands and displaced millions.

The junta-led states have distanced themselves from former colonial ruler France, kicking out its troops and turning toward Russia as an economic and security partner instead.

The EU already halted part of its training of Mali's armed forces in 2022, citing the risk of Russian interference.

It still has a training mission known as EUTM Mali and a civilian crisis management mission, EUCAP Sahel Mali.

In December, Niger's ruling junta revoked the country's military partnership with the European Union, known as EUCAP Sahel Niger.