The prime minister has said the government will continue to act on scientific advice following news that bird flu has spread to Scotland.

It was confirmed on Wednesday evening that a dead swan found in Scotland has tested positive for bird flu.

Further tests later on Thursday confirmed that the bird has the highly pathogenic H5N1 strain.

The Scottish executive has already put in place a three kilometre exclusion zone around Cellardyke in Fife, near which the swan's body was found.

It means that all domestic fowl in the area must be kept indoors in a bid to prevent further spread of the disease.

A wider surveillance zone, with a radius of 10km, has also been set up.

Charles Milne, Scotland's chief veterinary officer, said the discovery of the body was "a very important development".

Debby Reynolds, the UK's chief veterinary officer, added: "We are already in a high state of readiness and I have every confidence that officials north and south of the border will work together to manage this incident successfully."

It was also stressed that there is no threat to public health.

"Avian influenza is a disease of birds and whilst it can pass very rarely and with difficulty, to humans this requires extremely close contact with infected birds, particularly faeces," said a government statement.

And Tony Blair said the Scottish executive and the UK government would "take the measures that are appropriate".

"We will act according to the advice that we get," he said.

But he also stressed that there is no need for widespread public concern.

"This is not a human-to-human virus," added the prime minister.

"It is something that is transmitted to poultry. It is only if humans are direct and very intensive contact with poultry that there is any risk involved."

Following the news, farmers are being urged to step up their biosecurity measures and be prepared to move poultry indoors.

Confirmation of the disease came as the government ran a simulation exercise of how it would react to an outbreak of bird flu - the exercise has now been called off.

A meeting of the government's emergency Cobra committee was also expected to discuss whether tighter restrictions on bird movements are needed and whether birds should be moved indoors.

The controversial issue of vaccination of poultry was also likely to be on the agenda.

However, it insisted that all necessary steps were being taken.