LONDON (Reuters) - Pupils and staff at a school in Walesare being offered anti-flu drugs after being in contact with achild suspected of contracting bird flu in an outbreak of amild strain of the virus, health authorities said on Monday.

Teachers and children at the school, which is close to afarm in Corwen, North Wales, where the H7N2 strain of bird fluwas discovered last week, were being treated with antiviralmedication as a precaution, the National Public Health Service(NPHS) said in a statement.

A total of 12 people have been identified as suffering fromthe flu, reporting "symptoms of a flu like illness orconjunctivitis" it said, but stressed no one was seriously ill.

It identified 142 people who may have had contact with theavian flu and said it could not rule out person-to-personcontact.

"Person-to-person spread would be very unusual but limitedspread of this type has been seen elsewhere in the past in somecases of bird flu," said Dr Marion Lyons of the NPHS.

"As a precautionary measure the NPHS is continuing to offerpeople who have had contact with individuals with this illnessantiviral medication to minimize the risk of spread. "

Authorities confirmed an outbreak of bird flu last Thursdayamong chickens at a farm in North Wales.

NOT H5N1

But it was the low pathogenic H7N2 strain of bird flu, notthe H5N1 strain, which is potentially deadly to humans and hascaused scares elsewhere in the past.

Lyons said that investigations into the H7N2 strain hadshown that when it spreads from person to person, the illnessbecome milder.

But she added: "Experience of this particular bird fluvirus in humans is limited so we are actively managing thepublic health response."

Britain has been on the watch for bird disease afterEurope's biggest turkey producer Bernard Matthews was forced todestroy 160,000 turkeys because of an outbreak of the H5N1strain of bird flu in England earlier this year.

The

World Health Organization says 186 people have died ofbird flu since the H5N1 virus resurfaced in Southeast Asia in2003. The virus has since spread throughout much of Asia, partsof Europe, the Middle East and Africa.

The presence of an H7 virus in poultry is treated seriouslyby animal health officials because scientists believe that,when allowed to circulate in poultry populations, a lowpathogenic virus can mutate into the highly pathogenic form.