Swine flu advice for high-risk groups including pregnant women and children was underlined by the Government today ahead of the launch of a new pandemic service.

The Department of Health said separate pieces of guidance were pulled together in a section of the NHS website because it "made sense to clarify existing advice and put it in one place".

With the virus spreading to thousands of Britons, officials have sought to calm fears as the UK awaits the arrival of a vaccine.

Pregnant women were identified early on as a high-risk group, but concerns were heightened after a woman with swine flu died last week shortly after giving birth prematurely.

The 39-year-old woman, who died in Whipps Cross Hospital, was named by her brother as Ruptara Miah.

The total number of deaths linked to swine flu now stands at 29 in the UK.

According to the NHS, pregnant women are more susceptible to infections because their immune systems are suppressed and are advised to avoid unnecessary travel and crowded places.

Other high-risk groups include people with long-term conditions, the over-65s and children under five.

A spokeswoman for the Department of Health said it had not yet decided how the vaccines, which are expected to become available from next month, would be prioritised.

Pregnant women could take antivirals and be given vaccines, she said.

She also denied suggestions couples were being advised to delay conceiving amid the swine flu outbreak and said there was "no need to panic".

"The pregnancy guidance is designed to cover a range of scenarios," the spokeswoman said.

"Swine flu is so far proving to be mild for the majority of people although for a small number it has been severe.

"We advise everybody to plan their pregnancy carefully - we are not advising women not to conceive.

"Mums-to-be are more vulnerable to any type of flu. It is particularly important that anyone who has existing health problems and is thinking about starting a family should talk to their GP first, as they normally would."

In a statement issued on Friday, the Royal College of Obstetricians and Gynaecologists and the Royal College of Midwives said that although swine flu tended to be a mild respiratory disease, there had been a small number of cases of severe illnesses among pregnant women and infants.

It said people should wash their hands frequently and dispose of used tissues, adding: "Pregnant women are advised to avoid crowded places when possible."

Meanwhile, advice for holidaymakers was released, warning Britons not to travel if they have swine flu.

As schools break up, the Department of Health advised people with the virus to delay journeys until symptoms had gone.

Officials also warned that visitors to a number of countries would have to face strict screening procedures as the illness spreads.

This was demonstrated in China, where 52 British schoolchildren and teachers were placed in quarantine in a Beijing hotel after four teenagers from London were diagnosed with swine flu.

According to the DoH, holidaymakers should take medication such as paracetamol with them and avoid public places if they fall ill.

People travelling to Europe should carry a European Health Insurance Card (EHIC), the advice added.

If they catch swine flu - symptoms of which are a high temperature as well as two or more of a list including headache, sore throat, runny nose and aching muscles - while abroad, they should not travel home until recovered.

Health Secretary Andy Burnham, who is due to give a statement to the Commons tomorrow, said: "I want families to go on their holidays and have a great time this summer, and mums and dads shouldn't worry unnecessarily about swine flu.

"But, just as they would anyway, parents should keep a close eye on their children's health.

"If you're going abroad, as ever, make sure you know where you can get medical advice and if you're holidaying in the UK, remember that from the end of this week alongside GP services, you'll also able to phone the national pandemic flu service hotline for advice."

A spokesman for Abta, which represents travel agents and tour operators, said: "It's very sensible advice and we would agree with it."

He added that the cost of cancellation due to swine flu would be covered by travel insurance.

The advice came as a senior adviser to the Government moved to calm concerns over the swine flu vaccine after questions were raised about whether it will have been sufficiently tested before it is used.

Professor Sir Gordon Duff, co-chairman of the Scientific Advisory Group for Emergencies, said the "benefits far outweigh the risks".

He added: "It is inconceivable that in the UK we would consider a vaccine without giving a full scientific appraisal of its benefits and theoretical risks. That is just what these risks are - theoretical."