Sting has called for the legalisation of marijuana.

The Fields of Gold singer insists America should spend the money it uses jailing users of the drug on tackling poverty and global warming.

Sting ... sounding off about marijuana.

Sting, 58, wrote on his blog how he feels marijuana users are imprisoned for a crime that doesn’t hurt anyone.

He said: "The ‘War on Drugs’ has failed - but it's worse than that. It is actively harming our society. Violent crime is thriving in the shadows to which the drug trade has been consigned.