Volunteers of the American Peace Corps have begun leaving villages in Nepal following a US embassy warning for their safety.
The US information centre in Kathmandu was bombed last Friday
The US State Department agreed to its embassy's request to allow the volunteers and families of diplomats to return home.
The department also posted a new warning that Maoist rebels might target American citizens.
The US information centre in Kathmandu was hit by two bombs last Friday.
The US embassy's spokeswoman, Constance Jones, said the Peace Corps volunteers were assembling in Kathmandu.
They are likely to leave for home shortly.
About 100 volunteers had been working across Nepal in health, education, environment and infrastructure sectors.
The State Department warning appeared on its website, saying the embassy had received information of possible Maoist attacks on US citizens "particularly in regions of the country under Maoist control".
It advised Americans against non-essential travel to Nepal and for those in the nation to avoid road travel outside Kathmandu.
The embassy asked the department to allow the departures after the bombings at the information centre.
It said the attack not only endangered lives but also violated international norms and laws.
No one has admitted responsibility for the attack, but Maoist rebels have long been threatening to attack American targets.
The rebels have been critical of the US for providing military and financial assistance to the government to bolster the anti-insurgency operation.
The US has provided $22m in security assistance over the past three years and on Monday announced an additional $1m.
The rebels have been engaged in an armed struggle since 1996 to replace the monarchy with a communist republic.
About 9,000 people have died since then.