The North Atlantic Treaty Organization could extend such support through its Support and Procurement Agency, the UN chief said in a recent letter to the Security Council.

Guterres said he is "convinced" of the need to create a UN support office for the G5 Sahel force, which comprises around 5,000 soldiers from Mali, Mauritania, Niger, Chad and Burkina Faso, which would be funded by contributions from the United Nations.

He said such a technique would be "the most effective approach to provide sustainable and predictable support to the Joint Force."

But the United States, the UN's biggest financial backer, has so far rejected the plan, which is favored by France and several African countries.

In June, US deputy ambassador to the UN Jeffrey DeLaurentis said his country wanted to maintain a clear separation between efforts to fight terrorism and efforts to maintain peace in order to protect the UN's neutrality.

For years, the United States has said it prioritizes aid to the Sahel countries directly, rather than ramping up UN involvement.

"The creation of the G5 Sahel Joint Force, despite the persisting challenges, is a strong manifestation of political will by the five core States of the Sahel that merits the support of the international community," Guterres said.

"While all interlocutors underscored their strong support to the G5 Sahel Joint Force as an exceptional initiative that warranted international support, there is no convergence of views within the international community on how best to support it," the UN chief added.

The Security Council, currently led by Kenya, is set to send representatives for a visit to Mali and Niger at the end of the month, in an effort to study the security situation.

Guterres pointed out that despite the African Union's willingness to take on an integral role in fostering cooperation in the region, "the AU stressed that it would require financial support by another donor" to manage logistical support of the Joint Force.

The UN currently provides fuel, water and food to the Joint Force through the Minusma peace-keeping mission in Mali, plus bilateral medical support arranged in the last few years.