German Chancellor Angela Merkel said on Monday the World Health Organization must streamline its management to respond quickly to crises like West Africa's "Ebola catastrophe" that has killed more than 11,000 people.

The WHO and its director-general Margaret Chan have come under heavy fire for their slow response to the Ebola epidemic, which began in Guinea in December 2013 but was not declared an international public health emergency until August 2014.

"We ought to have reacted far earlier," she told the opening session of the annual meeting of WHO's 194 member states. WHO officials in country and regional offices and the Geneva headquarters must know immediately what to do in a crisis.

"I am convinced that if we act faster and have a clear command structure in place, we will be better equipped to combat a crisis like Ebola next time that happens," she said.

"The WHO is the only international organization that has universal political legitimacy on global health issues. This is why it is so important to render its structures more efficient."

Merkel said Germany would contribute 200 million euros to help developing countries boost their defenses against infectious diseases, including 70 million euros for West Africa.

Guinea has seen a spate of new Ebola cases due to transmissions at funerals, a worrying sign as it seeks to stamp out the epidemic, a health official said on Friday. ID:nL5N0Y63JH]

Liberia became the first of the three hardest-hit countries to be declared free of the virus this month, completing a 42-day period without a case.

Germany, which has the G7 rotating presidency, also seeks to help countries build up health systems to confront neglected tropical diseases that affect 1.4 billion people worldwide, Merkel said.

Another priority was ensuring the effectiveness of antibiotic drugs for treating both humans and animals, and combating the build-up of anti-microbial resistance due to overuse, she said.

Chan was due to address the assembly later on Monday and speak with reporters. On Tuesday, the talks are due to take up an interim report on WHO's handling of the Ebola outbreak.