NATO's chief says member nations must urgently provide more trainers for Afghanistan's expanding army and police if they are to assume responsibility for security as planned.

Secretary-General Anders Fogh Rasmussen says NATO's training mission is still short of 21 training teams for the Afghan army, and of over 100 teams for the police.

He says defense ministers from NATO's 28 nations meeting this week in Istanbul must address that shortfall. Gradually handing over security duties to the Afghans is a key element in the U.S. and allied exit strategy.

Major world powers last week decided to boost Afghanistan's military to 171,600 by October 2011, up from the current 98,000 troops. They also decided to increase police numbers to 134,000, from about 90,000 today.