Obama said Wednesday the US would set up a rapid response force to support United Nations and African Union peacekeeping missions.

"We will join with six countries that have demonstrated a track record as peacekeepers," he told reporters at the conclusion of a three-day summit of 50 African nations in Washington.

"We're going to invite countries beyond Africa to join us in this effort because the entire world has a stake in the success of peacekeeping in Africa," Obama added.

Ethiopia, Ghana, Rwanda, Senegal, Tanzania and Uganda are to be the six countries involved in the effort, he said.

Obama did not specify how the new peacekeeping plan would relate to existing African Union missions.

More testing for Ebola drug

Obama said the experimental Ebola serum given to two patients in the US will continue to be tested because it is too soon to know whether the treatment is successful.

"We've got to let the science guide us and I don't think all the information is in on whether this drug is helpful," he said. "The Ebola virus both currently and in the past is controllable if you have a strong public health infrastructure."

The priority, Obama said, was devoting resources to fighting the disease in the region.

"Let's get all the health workers we need on the ground. Let's nip as early as possible any additional outbreaks of the disease," he said. "During that process, let's see if there are additional drugs or medical treatments that can improve survivability of what is a very brutal disease."

West Africa is currently in the midst of the worst-ever Ebola outbreak, which has claimed more than 900 lives. Liberia's President Ellen Johnson Sirleaf on Wednesday declared a state of emergency in her country.

"The government and people of Liberia require extraordinary measures for the very survival of our state and for the protection of the lives of our peope," said said in a statement on national television.

Emerging Africa

The US president said the continent continues to face many challenges, but a new, more prosperous Africa is emerging.

Earlier on Wednesday, Obama called on African nations to be forceful in solving healthcare, security and government corruption problems that hinder progress on the continent.

He said the US was working with Africans to develop an "early warning and response network" to identify emerging crises.

dr/lw (AP, AFP, Reuters, dpa)