Over 100,000 people have signed a petition started by Green MP Caroline Lucas and backed by comedian Russell Brand calling for a full review of drug laws.

It challenges politicians to hold a parliamentary debate on Britain’s failed drugs policy.

Signatories hit 100,000 yesterday, meaning that Ms Lucas’s call for an independent assessment of the 1971 Misuse of Drugs Act must be considered for debate in Parliament.

The Brighton Pavilion MP said: “I’m absolutely delighted that so many people have sent a clear message to the government that we need a fresh approach. Today we have achieved an enormous step towards an evidence-based drugs strategy.”

The call has garnered support from many prominent figures and organisations including Richard Branson, campaign group Avaaz and drug policy experts.

Ms Lucas said: “The Misuse of Drugs Act is hopelessly out of date. It has never been reviewed, or undergone a cost-benefit analysis.

“In England and Wales alone, an estimated £3 billion a year is spent fighting the war on drugs, to little effect.

“Over half of the people in prison are thought to have serious drug problems and yet we continue to fail to treat drug addiction as the serious health problem it is.

Mr Brand put his weight behind the petition saying that current drug laws urgently need “sane” reform “based on something called evidence.”

The comedian said: “Almost 2,000 young people die in the UK each year from taking illegal drugs of uncertain potency, that they can only get hold of on the illegal market.

“Leading police, doctors, and politicians agree prohibition has completely failed to curb addiction.”

Avaaz campaign director Alice Jay contended that the public mood is moving away from the country’s current drug laws.

She said: “This petition shows people want politicians to step up and change Britain’s disastrous drug laws. Experts agree it is one of the most counterproductive policies we have.”

The campaign comes days after Deputy Prime Minister Nick Clegg called for drugs laws to be overhauled based on evidence.

“If you are anti-drugs, you should be pro-reform,” he said.