Western powers condemned Moscow for providing “material support” for the Russia-backed Vagner Group that has deployed mercenary fighters in the troubled West African nation of Mali.

Canada, Germany, France, and Britain -- which are involved in the fight against an Islamist insurgency in Mali -- and 11 other countries on December 23 said in a joint statement that they "firmly condemn the deployment of mercenary troops on Malian territory."

Western nations have previously raised concerns and implemented sanctions against the Vagner Group following its involvement in conflicts in Syria, Libya, the Central African Republic, and in eastern Ukraine.

They have warned Mali against deploying the group's forces, saying a reported deal between the country and the private military contractor would divert money away from efforts to fight terrorism and could ultimately destabilize the region.

The United States did not sign the statement, but the U.S. State Department on December 15 said Vagner Group forces “will not bring peace to Mali, but rather will destabilize the country further."

The declaration by the 15 Western powers on December 23 was one of the first major statements to acknowledge that the deployment of mercenary fighters had begun.

The statement did not say if the presence of the Vagner Group could eventually lead the countries to pull their own forces out of Mali.

"This deployment can only further deteriorate the security situation in West Africa, lead to an aggravation of the human rights situation in Mali [and] threaten the agreement for peace and reconciliation in Mali," the 15 powers said.

The statement said they "deeply regret" the decision by Mali’s leaders to use "already scarce public funds" to pay mercenaries instead of using the funds to bolster the country's owned armed forces.

"We are aware of the involvement of the Russian Federation government in providing material support to the deployment of the Vagner Group in Mali and call on Russia to revert to a responsible and constructive behavior in the region."

Mali has struggled against the Islamic extremist insurgency for the past decade.

Extremists were forced from power in the country's north with the help of a French-led military operation that began in 2013.

However, the rebels regrouped in the desert and began launching attacks on the Malian army and its allies.

France now has some 5,000 troops in the region, but plans to lower that number to 2,500-3,000 by 2023.

In June, Colonel Assimi Goita seized power and was sworn in as president of a transitional government in Mali after carrying out his second coup in nine months.

Facing increasing isolation from the international community, his government has scheduled elections for February, but there are fears they will be delayed or canceled.

U.S. State Department spokesman Ned Price earlier this month described the United States as “alarmed” by the potential deployment of Vagner Group forces in Mali under a deal that reportedly would cost $10 million a month.

His statement noted that Yevgeniy Prigozhin, a Russian businessman and close associate of President Vladimir Putin who is believed to run the Vagner Group, is sanctioned by the United States, Britain, and the European Union “in connection with his dealings with the Russian Federation's Ministry of Defense and his efforts to subvert U.S. democratic processes.”

Putin has said the Vagner Group does not represent the Russian state and is not paid by it. He has also said private military contractors have the right to work and pursue their interests anywhere in the world as long as they do not break Russian law.

With reporting by AFP and AP