Swiss researchers say they have developed an injection that takes the pleasure out of smoking.

Swiss pharmaceutical firm Cytos says 40% of a test group that took part in a nine month study quit smoking.

Before the injection the participants had all smoked between 10 and 40 cigarettes a day.

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Cytos has now patented the vaccine, CYT002 - NicQb, which works by building antibodies in the blood that stop nicotine from getting to the brain. When nicotine reaches the brain it leads to increased levels of the pleasure-releasing chemical dopamine, but the injection blocks this process - leaving the smoker with no kick.

The jab, which is required once a year, is expected to be on the market by 2010 at the latest.