Africa may be entering a period of "persistent famine" with drought striking more often, and aid agencies urgently need more money to combat the scourge, according to U.N. officials.

"There is a change in the world's weather pattern that disproportionately affects Africa," James Morris, director of the World Food Program, told reporters in London.

Although disasters have struck from the Asian tsunami to the Pakistani earthquake to flooding in Latin America, "the toughest issues are in Africa, there's no question," Morris said Tuesday. "We've been stretched to our capacity. Overwhelmed."

Morris said his U.N. agency is feeding some 20 million people affected by the latest drought in Africa. It has had to repeatedly ask for help and still, for example, needs $189 million for Kenya, where some 3.5 million people need help

In Somalia, WFP fed 1.7 million people last year for a few months, but this year about the same number will need help for six to eight months, possibly longer, he said.

"We are now entering a time of persistent famine" in Africa, Calestous Juma, a development expert from Kenya now at Harvard University, said in a telephone interview. His homeland is experiencing its worst drought in a decade.

Juma said Africa is moving from one drought to the next more quickly. He said that after each disaster, countries are slower to recover because they lose seeds and are not prepared for the next planting.

Douglas Keatinge of Oxfam who has worked with Kenya's cattle-herding peoples, said pastoral families in eastern Kenya have seen 90 percent to 95 percent of the herds they depend on for survival starve to death.

The more frequent droughts mean WFP has to mount a "more sustained emergency response," Morris said.

WFP is looking for new ways to fund its programs, including getting more from Arab donors, Morris said. He said half the agency's work is now in countries that are members of the Organization of the Islamic Conference, while less than 1 percent of its funding comes from Arab countries.

WFP and other U.N. agencies recently opened offices in the United Arab Emirates to work to increase Arab nations' donations from the current to at least 10 percent, Morris said.