An Essex University study has shown the illegal drugs market in Britain is worth £5 billion a year.

The giant annual spend means substance-abusers are spending more than two-fifths of the amount paid annually in Britain for legal alcoholic drink.

A team of six academics was commissioned by the Home Office to work out the figure, using records of thousands of interviews with both criminals and members of the public.

They estimated sales of highly-addictive crack cocaine alone were worth £1.48 billion a year in 2003-04, while £1.2 billion was spent on heroin.

Users of powder cocaine splashed out £973 million between them, while cannabis users spent £1.03 billion.