PANDI (Philippines) - UN EXPERTS on Thursday began collecting samples from two Philippine pig farms closed by an outbreak of Ebola-Reston virus.

The 22-man team aimed to collect blood and tissue samples from dozens of pigs to determine how they contracted the disease, said team leader Caroline Benigno of the Food and Agriculture Organization.

'We are here to conduct a field investigation. This is the start of the assessment to look for the cause of the Ebola-Reston virus,' she told AFP.

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.

As of December, nearly 6,000 pigs at a farm here and in the town of Talavera had tested positive for the virus, which is not known to be harmful to humans but could have a devastating impact on the pig industry.

Ebola-Reston is also different from the ebola sub-types found in Africa that cause deadly fever in humans.

'We're here not only to do some sampling, but also to understand the situation,' said Peter Ben Embarek, a public health expert from the World Health Organization.

He said it would take a while for the team to trace the source.

Farmhands and slaughterhouse workers have been tested since the outbreak was discovered and have so far been declared free of the virus.

The government however has issued a ban on the export of meat from the farms that are affected.

Ebola-Reston was first detected in 1989 in laboratory monkeys sent from the Philippines to Reston, Virginia in the United States. -- AFP