KABUL (Reuters):

Afghanistan's biggest challenge remains the Taliban insurgency, the head of a visiting United Nations mission said yesterday on the eve of the fifth anniversary of the overthrow of the Taliban's puritanical Islamist government.

The intensity of the Taliban's fightback this year has surprised NATO and United States-led troops in the bloodiest year since the group's ouster in 2001. More than 3,100 people, a third of them civilians, have died so far this year.

"I think the single most important challenge facing this country is insurgency, fighting the Taliban insurgency," Japanese Ambassador Kenzo Oshima told a news conference in Kabul after talks with government officials.

The illegal drug industry in the world's largest producer of heroin was another major challenge, he added.