Experts from three UN agencies have arrived in the Philippines to investigate an outbreak of the Ebola-Reston virus at two pig farms north of Manila, the World Health Organisation said on Wednesday.
Ebola-Reston, which is only found in the Philippines, had been confined to monkeys and the latest outbreak is the first time it has jumped species.
According to the WHO, the strain is not dangerous to humans, unlike the four deadly Ebola subtypes found in Africa.
The Food and Agriculture Organisation and the World Organisation for Animal Health are also represented in the mission.
"The fact that this is the first time that the virus has been found outside monkeys, and the first time ever, worldwide, that it has been found in swine, a food-producing animal, makes this mission particularly important," a WHO statement said.
It added the case had "potential implications for animal and human health and welfare".
The Philippine government quarantined the affected farms in Santo Nino and Pinagpanaan villages and halted pork exports when the virus was first detected in October.
The UN team was set to work with its Filipino counterparts over 10 days to establish "the source of the virus, its transmission, its virulence and its natural habitat, in order to provide appropriate guidance for animal and human health protection.
"Preliminary results are expected in a few weeks at the earliest," said the statement.
Local authorities have been unable to find any sign of the virus among farmhands or slaughterhouse workers who handled the pigs.
Ebola-Reston was first detected in 1989 in laboratory monkeys sent from the Philippines to Reston in the United States.