Afghan police briefly fled from a town in Bakwa district in Farah province after four of them were killed in a roadside bomb attack as their 10-vehicle convoy returned from a day of eradicating opium plants. Taliban militants moved into the town and seized three vehicles before abandoning the area, local officials said.

In Bakwa, the roadside bomb targeted the province's police chief. He was uninjured, but four officers riding in his vehicle were killed. "Three policemen were killed on the spot, and another died of his injuries in the hospital today," district Police Chief Afgha Saqib told Deutsch Presse-Agentur Monday.

Saqib blamed the Taliban for the attack. The resurgent guerrilla group is widely seen as benefiting from the drug trade in Afghanistan, which now produces more than 90% of the world's opium.

Taliban militants also seized the town of Musa Qala in Helmand province on February 1 and remain in control there. Helmand is now the largest opium producing province in the country.

Afghan President Hamid Karzai rejected US offers to spray poppy plants with herbicides and vowed to undertake an extensive eradication campaign this year. Last year, the Afghan opium crop grew by a whopping 49% over the previous year, producing an estimated 6,700 tons of opium, enough to make 670 tons of heroin.