The Philippines has discovered its first cases of bird flu with infected ducks being found in a town north of the capital, Manila, according to the BBC.

The trading of poultry has been banned for a week around the town of Calumpit in Bulcan province, the broadcaster said.

It is not yet clear if it is the H5N1 strain which has killed more than 50 people across Asia since 2003.

"There's no cause for alarm," said health secretary Francisco Duque, adding tests were being carried out.

He said samples had been sent to Australia to see whether the Philippine bird flu strain was the same as that which caused human fatalities elsewhere in the region.

Agricultural secretary Arthur Yap said early indications were that the strain was not deadly to humans. "There is no sign of transmission and no ducks have died," he said. "It is a low-risk flu strain found in three healthy ducks and the risk to human health is almost nil."

Yap said the cases were confined to a "small isolated farm". A 3km exclusion zone has been imposed on the affected area. "We are very lucky we caught it in a very early stage and we are confident that we can contain it," he said, adding that the virus had been detected during routine testing.

All birds on the affected farm are to be culled as a precautionary measure.

Mr Yap and other officials ate fried chicken at a press conference to demonstrate their message that chicken and duck remain safe to eat.

The Philippines has a large poultry industry, employing 300,000 people and worth 150bn peso (US$2.72bn) a year.

It is the only Asian country with large-scale poultry farming which has not yet been affected by the bird flu virus.

Fears about the H5N1 virus have led to the slaughter of millions of chickens and ducks across Asia in the last 18 months.

The WHO is alarmed that the more the virus spreads, the greater the chances it could combine with the human flu virus and trigger a flu pandemic.