The killer virus which killed at least 100 people in Malaysia and led to the slaughter of thousands of pigs has been identified.

Malaysian medical authorities initially blamed a mosquito-borne disease called Japanese encephalitis for the deaths.

Later, the previously undescribed virus called Nipah was held to be responsible.

Pigs suspected of infection were destroyed

Now, the Lancet medical journal has published a report by doctors in Malaysia and the United States confirming that the Nipah virus was the cause of the mystery illness.

It is thought to be a brand new disease that has crossed only recently from animals to people.

In a separate report, doctors in Singapore say the Nipah virus was also responsible for an outbreak of fever and drowsiness among abattoir workers there in March this year.

They say the 11 workers infected - one of whom died - were employed at an abattoir that imported pigs from a farm in Malaysia that was affected by the virus.

Researchers are now awaiting further test results on pigs, horses, dogs and other domestic animals to see if they can find out more about the virus and where it has come from.

Dr Nicholas Paton from Tan Tock Seng Hospital in Singapore says the virus appears to have spread from bats to pigs, and then to people, but nobody knows why.