Seven people in Wiltshire are being tested for swine flu, NHS Wiltshire has confirmed this lunchtime.

The health authority is not confirming where the people are from but say they have all shown mild symptoms of the disease, which is thought to have killed 152 people in Mexico.

All seven, who have either recently returned from Mexico or have links with someone who has, are being kept at home until the test results are known. Hospital treatment has not been required.

Results of mouth swab tests are expected to be announced this afternoon.

Emergency contingency plans between Wiltshire PCT, the police and health services, which were tested last year following a feared outbreak of deadly bird flu, are being put into action.

Maggie Rae, joint director of public health in Wiltshire, said: "The people concerned have reported minor signs and symptoms of flu. They have been very sensible in contacting the NHS as they had returned from Mexico and were concerned they had flu."

Mrs Rae said if any of the cases were confirmed as swine flu then it was likely anti viral drugs would be offered.

An incident room has been set up at NHS Wiltshire’s headquarters at Southgate House, Devizes, to co-ordinate the response to swine flu.

Health staff are answering telephone calls from GPs, practice nurses and Neighbourhood Teams wanting advice.

Mrs Rae said: “We have been very busy with quite a lot of queries. This morning there was a call every five minutes.”

She also urged people who suspect they might have flu not to go to their GP surgery but to phone them or NHS Direct on 0845 4647.

The advice being issued to Wiltshire residents is to adopt good hygiene practice - to cover your mouth and nose when coughing or sneezing, disposing of dirty tissues promptly in the bin and washing hands frequently.

The deadly swine flu virus could infect up to 40 per cent of the UK population in the next six months if the outbreak becomes a pandemic, world health officials said today.

Professor Neil Ferguson, a member of the World Health Organisation (WHO) taskforce which decided to raise its alert over the virus to level four last night, said four in 10 people could be infected if the country is hit by a pandemic.

But Prime Minister Gordon Brown said Britain was "among the best prepared countries in the world" and added that the Government was taking "all the urgent action that is necessary" to help prevent the spread of the virus.

Two cases of swine flu have already been confirmed in Falkirk, Scotland and cases have also been confirmed in the USA, Canada and Spain.

Earlier today, Britons were warned to avoid all but essential travel to Mexico as the WHO said the deadly swine flu virus can no longer be contained and raised its alert to two lower than the maximum of six, signifying a "significant increase in risk of a pandemic".

The Foreign Office said: "We are now advising against all but essential travel to Mexico."

It added that British nationals "resident in or visiting Mexico may wish to consider whether they should remain in Mexico at this time".

The two confirmed patients in the UK, Iain and Dawn Askham, of Polmont, near Falkirk, had been on honeymoon in Mexico and were being treated today in isolation at Monklands Hospital in Airdrie, Lanarkshire.

UK holiday company Thomson said it was cancelling two outbound flights from the UK to the Mexican resort of Cancun today and repatriating holidaymakers already in Mexico.

The flights to Cancun had been due to leave from Manchester at 9.30am and from Gatwick at 9.15am.

Thomson said it was now making arrangements to get clients home from Mexico and that repatriation flights were expected to start today.

The company said: "While we do appreciate that the new news may be a great disappointment to customers, we hope they will also understand that their health and safety is of paramount importance to us."

It added that flights due to operate to Mexico from tomorrow onwards were under discussion and decisions would be made later today.

Have you recently been to Mexico or know of anyone in Wiltshire who has been? Were you planning to visit Mexico but have now cancelled your trip? Call our newsdesk on 01225 773638.