THE United States is winding down efforts to destroy poppies in Afghanistan, blaming its zealous approach for pushing peasants towards the Taliban.

Richard Holbrooke, the special envoy for Afghanistan and Pakistan, said on Wednesday that President Barack Obama's Administration was making "significant adjustments" from the previous administration to try to root out Islamist extremism.

"We are downgrading our efforts to eradicate crops … a policy we think is totally ineffectual," Mr Holbrooke testified before Congress.

"Hundreds and hundreds of millions of dollars we've spent on crop eradication has not done any damage to the Taliban. On the contrary, it's helped them recruit," Mr Holbrooke said.

"In my experience," the US diplomat and negotiator said, "this is the least effective program ever."