Sierra Leone has declared a public health emergency to tackle the worst ever outbreak of Ebola and will call in security forces to quarantine epicentres of the deadly virus, President Ernest Bai Koroma said in a statement.

The measures resembled a tough anti-Ebola package announced by neighbouring Liberia on Wednesday evening. Koroma also announced he was cancelling a visit to Washington for a US-Africa summit next week because of the crisis.

Highly infectious Ebola has been blamed for 672 deaths in the West Africa nations of Liberia, Guinea and Sierra Leone, according to the World Health Organisation.

- Reuters