NATO head Anders Fogh Rasmussen said he would urge allies for more troops at a NATO defence ministers' meeting in Istanbul on Thursday and Friday.
"Allies and partners have made substantial contributions, but it isn't yet sufficient ... I will continue to push hard on this," he told a news briefing.
Rasmussen said one way to make up the shortfall would be for nations to reconfigure existing contributions to ISAF. "But I would not exclude the possibility that we will need additional contributions," he said.
"This training mission is of utmost importance to accomplish the strategy we all agree on. The more we invest in this transition now, the sooner the day when the Afghans can take responsibility themselves."
More than 110,000 foreign troops boost now the invasion in Afghanistan. The United States has committed another 30,000 and allies up to 9,000 more, with the aim of containing a widening Taliban influence while building up the strength of Afghan forces.
The attacks against Western-backed government has risen since invasion of U.S.-led foreign troops. The fighting between Western troops and Taliban fighters have killed hundreds of thousands Afghan civilians.
NATO has long tried to create enough trainers, particularly for the police, who are vital for creating the conditions to allow foreign forces to withdraw.
NATO officials say the current shortage amounts to 2,000-2,400 foreign trainers, who are needed to help build Afghan forces so they can take over responsibility for security.
However, Rasmussen said the alliance was still short of 21 teams to train the Afghan army and more than 100 teams to train the police. If Afghanistan's security forces are to grow to a target of 300,000 personnel in 2011, even more training teams will be needed, he said.
The European Union has promised to send 400 police trainers, but fewer than 300 have actually been committed since the launch of the mission in 2007, mostly because of safety concerns.
As well as on trainers, Rasmussen will make proposals in Istanbul for more troops.
NATO will also urge more cooperation in providing medical facilities and helicopters that the alliance requires.
ReutersLast Mod: 02 Şubat 2010, 09:29