Experts generally agree that a pandemic of some kind is overdue, and that H5N1 presents the most likely threat.

So far, however, it remains essentially an animal disease.

205 people have been infected in nine countries, causing 113 deaths, since bird flu re-emerged in Asia in 2003, according to the WHO, a United Nations agency. In the same time the disease has spread among birds in 45 countries.

BIRD FLU FATIGUE?

In an interview published on Wednesday the acting director of WHO's global influenza program had warned the world it needed to prepare for a long-term fight against bird flu and not give in to fatigue that seemed to have set in.

Keiji Fukuda said the virus's tenacity and persistence increased the risk that it might evolve into a pandemic.

Britain and Ivory Coast looked to be keeping up measures to stop the disease's spread.

The United Kingdom is to cull some 35,000 birds on a poultry farm in the east of the country after a strain of bird flu was detected in chickens.

Preliminary tests showed the virus was likely to be an H7 strain of bird flu, not H5N1, the government's chief vet said.

The Department for the Environment, Food and Rural Affairs said all birds on the farm near Norwich, an area home to some of Europe's biggest poultry farms, would be killed as soon as possible as a precautionary measure.

Ivory Coast also prepared to slaughter chickens and tightened restrictions on poultry movement after reporting outbreaks in two populous parts of its main city Abidjan.

The World Organization for Animal Health (OIE) said late on Wednesday birds infected with H5N1 had been found in separate outbreaks in the Marcory Anoumabo and Treichville suburbs.

Two local clinics had made the diagnosis, which the OIE expected to be confirmed by its own laboratory in Padua, Italy.

"We are going to start killing all poultry in a 3 km (2 mile) radius around the site that has been declared positive," said Bakary Cisse, head of the government's animal disease surveillance task force.

Myanmar appeared to have scored a success with its program of culling and restrictions in recent weeks though, with the U.N. Food and Agriculture Organization agreeing with a decision to lift a ban on the sale and movement of poultry within days.

FAO chief technical adviser Ram Chaudhary said the tough restrictions were no longer necessary because no new outbreaks had been reported for 3 weeks.

"Myanmar was very strict. They had closed down the poultry markets. Nobody could prepare or sell chicken on the street."