The U.S. Peace Corps began evacuating 340 volunteers from West Africa as Liberia promised to quarantine communities, close border-town markets and limit public gatherings to prevent the spread of deadly Ebola.

Two Peace Corps volunteers are being monitored after contact with a person who later died of Ebola, said Shira Kramer, a spokeswoman, in an e-mail. They don’t have symptoms and will return to the U.S. once they get medical clearance. Other aid groups urged the international community to provide more funding and supplies for workers fighting the outbreak.

“The countries just aren’t prepared for something like this,” said Fiona Mclysaght of Concern Worldwide, a Dublin- based relief organization. Sierra Leone “already has a high level of child and maternal mortality. It has a very weak health system.”

Many of the needs are very basic, Mclysaght said by telephone from Sierra Leone, where she is based. It includes a “real shortage of gloves” among community workers.

The actions announced yesterday by Liberia’s president, Ellen Johnson-Sirleaf, are the most drastic taken by a government in response to the outbreak. The country’s security forces have been ordered to enforce the new measures, Johnson- Sirleaf said.

Ebola has killed 672 people in four West African nations since March, including 129 in Liberia, the worst outbreak since the virus was first reported in what is now the Democratic Republic of Congo in 1976.

“The government will do its part, but you must do yours,” Johnson-Sirleaf said yesterday in a televised speech to her country. “Denying that the disease exists is not doing your part to keep yourself and your loved ones safe.”

The U.S. White House also weighed in yesterday. Eric Schultz, a spokesman for President Barack Obama, said Obama is receiving regular updates on the situation in West Africa.

The government is “continuing to provide a range of support and assistance to those countries and multinational organizations responding to the outbreak,” Schultz said. The schedule for a planned Africa summit in Washington with leaders from that continent hasn’t been altered, he added.

“We have no higher priority than the protection of U.S. citizens overseas,” Schultz said during a briefing with reporters. “But again, as the CDC has stated there’s no significant risk to the United States,” he said referring to previous comments from the U.S. Centers for Disease Control and Prevention.

Robert Quigley, a doctor and official at International SOS, a London and Singapore-based medical and travel security services firm, said they had a 400 percent increase in requests for advice and information from May to June.

“It’s bringing back memories of the SARS endemic, which began in Asia and ended up over in Canada,” Quigley said by telephone. “It’s very reminiscent of the level of alertness.”

The difference between the outbreaks is that “with this disease, if you’re using proper hygienic practices and proper equipment, you should be able to protect yourself from contamination.”

This isn’t the first time the Peace Corps has suspended operations in a country because of health concerns. All volunteers left China in 2003 because of the SARS outbreak there, then returned the next year, according to Kramer, the group’s spokeswoman.

The Peace Corps decision to leave West Africa follows by a day the announcement by two North Carolina-based charities providing medical care in Liberia that they would evacuate workers who aren’t essential to the Ebola efforts.

Two Americans volunteering with those groups, Kent Brantly and Nancy Writebol, were infected with Ebola and are still receiving intensive care at the isolation center in Monrovia, Liberia’s capital, according to a statement released yesterday by Samaritan’s Purse.

Treatment relies on the immune system to fight off the disease. Patients are given replenishing fluids, their blood pressure is maintained through infusions, and infections are fought with antibiotics. There is no cure for Ebola.

The World Health Organization and other international groups are stepping up the response to the outbreak, said Catholic Relief Services country director Meredith Dyson by phone from Bo, Sierra Leone.

While there have been reports of unrest and attacks on some medical workers, Dyson said her group, which has about 140 local staff, is using established relationships within the communities it serves. They’ve stopped organizing large gatherings and limit travel by workers in regions with a high number of cases, she said.

Now the focus has turned to radio and less direct education efforts, Dyson said.

Doctors Without Borders is shifting more resources toward Sierra Leone, according to a statement on the group’s website. Even supplies at treatment centers can be limited, said Billy Fischer, a doctor with the University of North Carolina at Chapel Hill who returned to the U.S. after working on the Ebola response in Guinea on June 10.

“We did not have ability to check potassium and magnesium levels,” Fischer said in a telephone interview. That’s essential for Ebola patients who may be vomiting or have diarrhea and experience dangerous dehydration, he said.