A health warning has been released after an outbreak of the potentially fatal Legionnaire's disease in central London.

Three people who had stayed in the Portman Square area, near Oxford Street, have contracted the disease. One of them is seriously ill.

Westminster Council was notified about the cases between 1 and 19 June, but the onset of the illness could have started earlier.

Kai Lau, a consultant for communicable disease control at Kensington, Chelsea & Westminster Health Authority said:"Anyone in the immediate vicinity of Portman Square in mid-May who has subsequently suffered from serious flu-like symptoms should contact their doctor for further advice."

Treatable

The council will not say the exact location of the outbreak as there are legal considerations.

Early symptoms of the disease resemble those of flu.

It usually begins with a headache, pain in the muscles and a general feeling of being unwell, followed by a high fever and shaking chills.

Legionnaire's is most often treated with antibiotic drugs and can take several weeks to recover from.

It is transmitted by breathing in droplets contaminated with legionella bacteria and is fatal in approximately 5% to 15% of cases.

The bacteria is normally found in ponds, water systems and air conditioning cooling towers.