WASHINGTON: US regional military commander General David Petraeus on Wednesday called Washington's fight against terrorism in Afghanistan "successful," even if Al-Qaeda leader Osama bin Laden has not been captured.

"There has always been a significant focus of resources to get Bin Laden, and while he hasn't been caught, the effort has been successful in the overall fight against terrorism," said Petraeus, chief of US Central Command, speaking from Kabul to Fox News channel television.

Petraeus said that even if bin Laden remains at large, "as a result of some of those efforts significant numbers of top 20 extremist leaders have of course been killed, and in some cases captured and removed from the picture."

Addressing the issue of efforts to train sufficient number of Afghan troops to succeed the United States ahead of an eventual troop pullout, Petraeus said "it will not be easy to reach the goals we have for next year or for subsequent years."

"It's very important we train as many as we can, as quickly as we can, without rushing to failure. Quantity does have a quality of its own but only if it has a reasonable quality as well," the general said.

President Barack Obama earlier this month announced plans to send 30,000 more US troops into the war in Afghanistan, as US and NATO forces attempt to halt momentum by Taliban and Al-Qaeda forces and bring security to major population centers.