Violence erupted in an Ebola quarantine zone in Liberia's capital when soldiers opened fire and used teargas on crowds as they evacuated a state official and her family.

Four residents were injured on Wednesday in the clashes in Monrovia's West Point slum (above) which has been closed off as part of new security measures aimed at containing the deadly virus.

The crackdown in Liberia comes as authorities around the world scramble to stem the worst ever outbreak of Ebola, which has killed more than 1,200 people across west Africa this year.

The Liberian president, Ellen Johnson Sirleaf, quarantined West Point and Dolo Town, to the east of the capital, and imposed a night-time curfew as part of drastic measures to fight the disease.

Residents of West Point, where club-wielding youths stormed an Ebola medical facility on Saturday, reacted with fury, hurling stones and shouting at the security forces.

"It is inhumane," one resident, Patrick Wesseh, told AFP. "They can't suddenly lock us up without any warning. How are our children going to eat?"

Liberia, where 466 people out of 834 diagnosed cases have died, has seen the biggest toll among the four west African countries hit by Ebola.

Deaths from the epidemic now stand at 1,229 after the disease claimed 84 victims in three days, according to the World Health Organisation.

Fears that the virus could spread to other continents have seen flights to the region cancelled and authorities around the world adopting measures to screen travellers arriving from affected nations.

Late on Wednesday, Vietnam said it had released two Nigerian air travellers from isolation after their fevers subsided. Meanwhile, in Burma, a local man is still undergoing tests after arriving from Guinea with a fever.