A major part of the violence in southern Afghanistan is due to opium poppy cultivation and drug trafficking, the commander of NATO forces in the troubled country said Saturday.

"I'm convinced that much of the violence is only caused by the drugs-related activities in the south," said British General David Richards, who on Monday assumes command for all the international troops based in violence-plagued southern Afghanistan.

There was an inextricable link between opium and the violence seen, for example, in southern Helmand province, he told a press conference.

Afghanistan is the world's main producer of opium, from which is derived morphine and heroin.

The drug traffickers benefitted from the near total absence of authorities representing the central government in the south and also the low number of international troops stationed in the area since the toppling of Taliban regime at the end of 2001, Richards said.

"The opium trade is being threatened by the NATO expansion into the south and they are going to fight very hard to keep what they have got and a lot of what we are seeing has nothing to do with any ideological commitment" to the Taliban, the general said.

Richards however stressed that there was no question of attacking poppy farmers, whom he said were more victims than perpetrators of the drug trade.

They would depend on the development plan, which NATO is stressing, to convince farmers to change their crops to ensure their livelihoods.

The anti-drug strategy in Afghanistan has so far borne little fruit. The United Nations expects an increase in poppy production this year despite efforts at eradication.