The Philippines will slaughter 6,000 pigs at a hog farm north of the capital Manila to prevent the spread of the Ebola-Reston virus, health and farm officials said on Monday.

But the government has lifted a quarantine on a second hog farm after tests by experts from the World Health Organisation (WHO), World Organisation for Animal Health (OIE) and Food and the Agriculture Organisation (FAO) showed no more signs of the disease.

The country has more than 13 million heads of swine and the discovery of Ebola-Reston on two hog farms north of Manila was isolated, the government said.

"There is ongoing viral transmission in Bulacan ... as a precautionary measure, depopulation will be carried out in the Bulacan farm," Health Secretary Francisco Duque told reporters, referring to the farm just north of Manila.

The government said 6,000 pigs would be killed, burned and buried as experts sought to determine the source of Ebola-Reston in pigs as well as pig-to-pig and from pig-to-human transmission. Duque said 147 human samples have been tested for Ebola, but only six have tested positive. But all six remain healthy, he added.

"Ebola-Reston poses a low risk to human health at this time," Duque said.

It is the first time the virus has been found outside monkeys and the first time it has been found in pigs. The virus had previously jumped from monkeys to humans but this was the first case of a jump from hogs.

The Ebola-Reston virus was found in the Philippines as early as the late 1980s and 25 people were found infected after contact with sick monkeys. But only one developed flu-like symptoms and later recovered.