PIRBRIGHT, England, Aug 9 (Reuters) British abattoirs resumed the slaughter of animals today after

PIRBRIGHT, England, Aug 9 (Reuters) British abattoirs resumed the slaughter of animals today after the government lifted a five-day ban on the movement of livestock following an outbreak of foot and mouth disease.

A third herd of cattle suspected of infection with the highly contagious disease was identified late yesterday and immediately culled, officials said. Tests to confirm the infection are still being carried out.

In total, 576 head of cattle have been culled as a result of the disease outbreak, first confirmed in a herd last Friday.

All the culled cattle were in herds within a 10-km (6-mile) surveillance zone around the farm where the first cases were discovered, raising hopes among Britain's farming community that the outbreak has been contained.

Farmers were also cheered by the lifting of a ban on the movement of animals for slaughter.

In 2001, a devastating foot and mouth outbreak led to more than 6 million animals being culled, many burnt on vast funeral pyres. Rural tourism was also hit and the cost to the economy was 8 billion pounds (16 bln dlr).

Following the latest outbreak, the European Union banned all imports of British livestock, meat and dairy products and is not expected to review its policy until August 23.

Britain's livestock industry has annual meat exports worth more than $1 billion and a long export ban would hit it hard.

Abattoir workers said the lifting of the movement ban had caused chaos, with a huge backlog of animals being brought in for slaughter.

''The animals can be moved direct from farm to slaughterhouse, we're getting that bit done all right, but the rest of it is all backed up,'' said Roger Carr, owner of the Simply Halal abattoir near Milton Keynes in Buckinghamshire.

''It's chaos. We can't move the skins, we can't move the green offal (the intestine and stomach of cows), we can't move the effluent.'' INSPECTIONS As well as trying to contain the spread of the disease, which affects cloven-hoofed animals, health inspectors are trying to pinpoint the source of the foot and mouth outbreak.

Suspicion has focused on Pirbright, a research site about 5 miles (8 km) from where the cattle were infected. This houses two foot and mouth laboratories -- one the government-run Institute for Animal Health and the other operated by Merial, a private US-French animal vaccine manufacturer.

Both laboratories handle various strains of foot and mouth virus, including the uncommon strain that infected the cattle.

Both laboratories have said they follow the strictest bio-security measures and there is still no hard evidence that the virus somehow leaked from either of their laboratories.

However, government inspectors have said there is a ''strong probability'' the disease originated at Pirbright.

The National Farmers' Union, which represents farmers nationwide, has retained lawyers in case it is found the spread of the disease was caused by negligence or human activity.

''This (preliminary legal) work will involve taking advice on potential grounds for a legal claim in the event that it is confirmed that the foot and mouth virus came from one of the sites at Pirbright.'' Merial, one of the world's leading animal health companies, is owned by US firm Merck and French firm Sanofi-Aventis SA.

REUTERS AE RAI2336