David Cameron came under attack from safety campaigners today after he was pictured cycling without wearing a helmet.

Headway, the brain injury association, said it was "deeplydisappointed" to learn of photographs taken of the Conservative leaderleaving his home and arriving at the House of Commons on his bicyclewith his safety helmet dangling from his handlebars.

Luke Griggs, Headway spokesman, said: "Brain injury can happenat any moment - all it takes is just one fall and you will regret itfor the rest of your life. We are deeply disappointed.

"Mr Cameron should be proud to be seen to be wearing hishelmet. He should be setting a good example to cyclists, particularlyyoung cyclists in the UK."

A Royal Society for the Prevention of Accidents (RoSPA)spokeswoman said: "We encourage cyclists to wear helmets, obviously itis not the law, at the end of the day it is a personal choice. But wedo encourage people to wear helmets.

"Helmets will not stop an accident from happening, but it will hopefully reduce the severity of injuries suffered."

But a London Cycling Campaign spokesman said: "We take the viewthat people should make their own informed decisions about the wearingof helmets.

"The evidence of the protective ability of helmets in the event of a collision with a vehicle remains unclear."

The Conservative leader, in dark clothes, trainers, and wearinga fluorescent sash, pedalled the distance from his home in west Londonto the House of Commons.

He was accompanied by two men on bicycles, believed to be special branch officers, and a man thought to be a "cycling buddy".

It is not the first time he has been criticised over cycling without a bicycle helmet.

In 2006, MPs and safety campaigners claimed his habit ofremoving his helmet for the cameras was setting a bad example tochildren.