Britain said yesterday a third suspected outbreak of foot-and-mouth had been found in southern England but a ban on sending animals to slaughter was lifted in most of the country.

Investigators were still searching for the cause of the outbreak of the highly infectious animal disease with the investigation focusing on research laboratories close to the infected area.

"I have this morning ordered culling (of farm animals) on suspicion of foot-and-mouth disease on one farm adjacent to the second infected premises... I cannot rule out that disease is developing on the premises," Britain's chief veterinary officer, Debby Reynolds, told a news conference.

After the first outbreak was confirmed on a farm in Surrey, southern England, last Friday the government banned the movement of animals to prevent the disease from spreading. Foot-and-mouth was found on a second, nearby farm a few days later. Ms Reynolds said the government would allow live animals to be moved direct to slaughter and dead animals to be collected from farms outside the affected area from midnight yesterday.