British Muslims travelling to Mecca for the Haji pilgrimage will need an injection against seasonal flu, it has been warned.
The Saudi Arabian government has said it will not issue travel visas until a certificate of a two-week old vaccination has been presented to a consulate, adding that a H1N1 virus vaccine will also be necessary, if it becomes available before November.
The World Health Organization (WHO) and the Saudi government have also advised at-risk groups such as pregnant women, children and the elderly to avoid attending Haji for their own safety.
Communities minister Shahid Malik said: "It is inevitable that at an event where two million people are expected to meet, viruses will spread quickly - and this year there is greater concern about flu, particularly for vulnerable people."
Around two million Muslims from across the world converge on Mecca - the holiest site in Islam - each year to take part in the pilgrimage.