Britain has helped Afghanistan destroy a massive quantity of poppy crops grown to supply the heroin trade.

The government announced on Tuesday that the interim Afghan government had achieved a major success in cutting the amount of opium poppies being grown.

Foreign Office minister, Denis MacShane, revealed the government had played key role in helping the country, which supplies 90 per cent of the heroin that reaches the UK.

A joint effort involving the International Development department, the Foreign Office and MOD had helped the Afghan government destroy 16,000 hectares of crops - an area half the size of the New Forest - with a value of £5 billion on UK streets.

"What this very good new about the opium poppy eradication programme indicates is that farmers are ready to turn away from opium poppy production, turn away from the drug barons and the drug traffickers," MacShane told the Commons.

Conservative shadow Foreign Office minister, Alan Duncan, gave his party's support to the announcement.

"I think both sides welcome any step that is taken towards crop substitution in Afghanistan," he said.