United States President Barack Obama will on Tuesday seek to "turn the tide" in the Ebola epidemic by ordering 3,000 US military personnel to West Africa and launching a major health-care training and hygiene programme.

The White House said Obama will travel to the Centres for Disease Control and Prevention (CDC) in Atlanta to meet US health chiefs and make the announcement, meant to spur a global effort to fight an outbreak that has already killed 2,400 people.

The announcement comes amid increasing alarm about the worst-ever outbreak of the disease which has spread through Liberia, Sierra Leone, Nigeria and the Democratic Republic of Congo.

Most of the new US effort will be concentrated in impoverished Liberia - the most badly affected nation.