The US military will send more than a thousand troops to Liberia in coming weeks as part of Washington's effort to counter the Ebola outbreak in west Africa, the Pentagon said Tuesday.

About 700 soldiers from the US Army's 101st Airborne Division and another 700 military engineers are due to deploy to Monrovia around late October, spokesman Rear Admiral John Kirby told reporters.

The soldiers will join nearly 200 US military personnel already on the ground, part of a total contingent of 3,000 troops to help train health workers and set up hospitals and other facilities. President Barack Obama earlier this month unveiled plans to send about 3,000 forces to Liberia to provide logistical and other help for efforts to stem the spread of the virus.

The troops from the 101st Airborne will form a headquarters that will be led by Major General Gary Volesky, who will take over in late October from the current commander of the mission, Major General Darryl Williams.

Kirby said the military was not leading the US government's effort but was in Liberia playing a supporting role to other civilian US agencies fighting the Ebola outbreak.

Military engineers are due to build new Ebola treatment centers in affected areas, with US aid officials due to recruit personnel to work at the units.

The Pentagon has said American troops will not have direct contact with patients with the virus.

The deployment plans were announced as the United States diagnosed its first case of the Ebola virus in a man who became infected in Liberia and traveled to Texas.