NATO's chief says the professionalism of Afghan security forces and their recent suppression of Taliban attacks in Kabul gave him confidence they will be ready to handle their nation's security by 2014.

NATO Secretary-General Anders Fogh Rasmussen said Thursday that Afghan forces are already leading 40 percent of security operations in Afghanistan ahead of the planned withdrawal of most international combat troops by the end of 2014.

"We have seen how Afghan security forces handle security incidents in a very professional manner," he told reporters.

He praised the work of Afghan forces in May in containing the Taliban's boldest and most complex assault in years when insurgents targeted embassies, government buildings and NATO bases in near-simultaneous attacks in Kabul.

"The Afghan security forces handled that situation and turned what was planned to be spectacular attacks into a spectacular failure," Rasmussen said.