UN Secretary-General Ban Ki-moon on Monday said that although new malaria cases have fallen by 18 percent since 2000, the world is still far from eliminating malaria, and Africa remains the biggest victim.

"In Africa, where the burden of malaria is greatest, the mortality rate has fallen by two-thirds," Ban said in his message for the World Malaria Day, which falls on April 25.

Between 2000 and 2015, an estimated six million deaths from malaria were averted, thanks in part to efforts linked with the Millennium Development Goals, a set of eight anti-poverty targets which was replaced in 2016 by the Sustainable Development Goals, the secretary-general said.

"The increase in global financing for malaria has yielded impressive results," he said, adding that more than half of the people in Africa are now protected by mosquito nets, up from less than 2 percent in 2000.

"The development and distribution of rapid diagnostic tests means cases can be identified and action taken quickly to prevent further spread of the disease," Ban said.

"Investment in malaria prevention and treatment is one of the most cost-effective ways to spend money," he said. "The World Health Organization estimates that anti-malarial efforts have saved 900 million (U.S.) dollars in healthcare costs alone since 2001, in addition to the economic contributions of people who would otherwise be sick."

"Today, on World Malaria Day, we should celebrate these remarkable achievements in the battle against one of the world's biggest killers," he said. "But sadly, we are still far from eliminating malaria."

Last year, there were 214 million new malaria cases and more than 400,000 deaths, he noted, adding that nearly nine in 10 cases were in Africa.

"Malaria is a formidable opponent, so there is no guarantee that progress will continue," he said. "If we lower our guard, experience shows that the disease may come back. Mosquitoes develop resistance to insecticides and malaria parasites can become resistant to medicines."

Ban has commend the World Health Assembly for setting ambitious goals for 2030: reducing malaria cases and mortality by at least 90 percent; and eliminating malaria in at least 35 countries.

"Reaching these goals will require significantly greater investment in fighting malaria. But it will take more than money," he said. "It will take political will and leadership."

"On World Malaria Day, as we celebrate our progress against this ancient killer, I call on everyone involved to redouble our efforts to reach the 2030 malaria goals," he said.

World Malaria Day is an international observance commemorated every year on 25 April and recognizes global efforts to control malaria.

World Malaria Day sprung out of the efforts taking place across the African continent to commemorate Africa Malaria Day. It is one of eight official global public health campaigns currently marked by the World Health Organization.