United Nations Secretary General Antonio Guterres vowed on Wednesday to pursue support for an anti-terror force gathering five Sahel nations, despite a US rebuff for UN funding.Guterres visited the headquarters of the so-called G5 Sahel on the second and final day of a trip to Mali, in the heart of the jihadist insurgency in the Sahel.After praising the G5 for its work, he said, "I was in favour of a stronger mandate" by the Security Council for the force.Despite the setback, the UN peacekeeping force in Mali, MINUSMA, will provide the G5 with all possible support, he said."We will put forward a very strong argument for the G5 to have the necessary financial resources and equipment to be effective," he said."We are also requesting (help for) development in the Sahel, because there is no peace without development," he said.Burkina Faso, Chad, Mali, Mauritania and Niger last year agreed to set up the joint force, which would comprise 5 000 troops with a mandate to confront jihadists in the vulnerable Sahel belt.It would operate alongside France's operation Barkhane.It was projected to be fully up and running in March, but its deployment has faced delays and the joint force is poorly-equipped.Guterres, as well as France, has been lobbying for the force to speed up its work and pushing for UN funding, which would be in addition to technical support from MINUSMA.But on May 23, the United States said it opposed a Security Council mandate for the force and direct UN funding. "The United States will not accept any proposal to move these forward in the Security Council," US political coordinator Amy Tachco told a council meeting in New York.The vast Sahel region has turned into a hotbed of lawlessness since chaos engulfed Libya in 2011, the Islamist takeover of northern Mali in 2012 and the rise of Boko Haram in northern Nigeria.About $570m have been promised for the G5 Sahel, mostly by European countries, Saudi Arabia and the United Arab Emirates. US support has been bilateral and relatively low - $60m was promised by then secretary of state, Rex Tillerson, in October.Guterres on Tuesday visited MINUSMA, heaping praise on the force which has suffered the most fatalities of any UN peacekeeping mission.MINUSMA has 12 500 military and police personnel, but has lost more than 160 people since it deployed in 2013 - a figure that accounts for more than half of UN peacekeeping fatalities over this period.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.