WASHINGTON (AFP) - The US Peace Corps announced on Wednesday it was pulling hundreds of volunteers from Guinea, Liberia and Sierra Leone due to growing concerns over the spread of the deadly Ebola epidemic raging in West Africa.

A Peace Corps spokeswoman said two volunteers had contracted Ebola after coming into contact with someone who later died from the virus, but she stressed that they were not symptomatic and were currently under medical observation and being held in isolation.

"When they receive medical clearance for return to the US, we will work with them to travel safely back," she added.

The US government-run volunteer agency said it would "closely monitor" the outbreak with US experts from the Centres for Disease Control and Prevention and State Department before a future return to the three countries, those most affected by the outbreak. It set no date for resuming operations.

"The Peace Corps has enjoyed long partnerships with the government and people of Liberia, Sierra Leone and Guinea and is committed to continuing volunteers' work there," it said in a statement.

At least three Americans have died from the virus, including one who died in Nigeria after contracting the virus in Liberia, State Department spokeswoman Marie Harf said.

While stressing there was no significant risk in the United States from the Ebola outbreak, Harf noted that health care providers were at the highest risk of contracting the virus.

There are currently 102 Peace Corps volunteers in Guinea working on agriculture, education and health, 108 in Liberia and 130 in Sierra Leone.

The three countries are struggling to contain an epidemic that has infected 1,200 people and left at least 672 dead across the region since the start of the year.

Fears that the outbreak could spread to other continents have been growing with European and Asian countries on alert and leading medical charity Doctors Without Borders warning the epidemic is out of control.

The Peace Corps said it had provided volunteers in adjacent areas to those countries with guidance to take the "utmost precautions" to protect their health in recent months.

Ebola, which first emerged in 1976, is believed to be carried by animals hunted for meat, notably bats.

It spreads among humans via bodily fluids and has killed 56 per cent of those it has infected in the current outbreak.