Measles immunisation rates are so low in the capital that health officials fear an outbreak of the disease.

A report from the London Assembly today has warned that only 52 per cent of London's children are fully immunised against measles, mumps and rubella compared to a national average of 74 per cent.

The report warns that London's current immunisation levels are well below that needed to prevent a severe measles outbreak.

According to the report the low rates are due to concern caused by allegations in the 1990s of a link between autism and the MMR jab.

The report noted that stories questioning the safety of the MMR jab still continue to appear in the media meaning parents were left unsure about the vaccine's safety.

Assembly member Elizabeth Howlett, who conducted the investigation on behalf of the London Assembly's health and public services committee, said: "Last year there were 640 cases of mumps, 271 cases of measles, and 16 cases of rubella in the capital. All of the diseases infants are vaccinated against are potentially serious and it is frightening to think about what could happen if we are faced with a serious outbreak. One thing is clear - we must do everything possible to reverse this downward trend and protect Londoners from disease."

Dr Mary Ramsay of the Health Protection Agency said: "The number of unvaccinated children in the capital has been mounting up, so that a serious outbreak of measles may be just a matter of time and circumstance: immunisation rates in some communities are so low that introduction of a person infected with measles could lead to large outbreaks difficult to control."

The report's authors called for more work to be down to bring the capital's immunisation rates up.

Recommendations include improving data collection and giving parents a clear and consistent message about vaccinations.

Immunisation rates in London Primary Care Trusts for children at their 5th birthday (per cent)

Area MMR first dose MMR second dose England 87 74 London 77 52 Croydon 87 57 Hounslow 82 64 Kingston 85 72 Richmond and Twickenham 77 64 Sutton and Merton 77 64 Wandsworth 66 51