WASHINGTON (Reuters) - NATO must remain focused on fostering stability in Afghanistan despite the protests and violence that have gripped the country following the burning of copies of the Koran on a NATO military base, the alliance's head said on Tuesday.

"Despite the tragedy of this incident and the challenges we face, we must not lose sight of our goal, a stable Afghanistan. That is in all of our interest; that must remain the focus of our shared effort," NATO Secretary-General Anders Fogh Rasmussen said during an alliance seminar in Washington.

The strategy of the United States and its NATO partners has been questioned in recent days, after the burning of copies of the Muslim holy book triggered widespread protests and two U.S. officers were killed in an attack that took place within the Afghan Interior Ministry.

(Reporting By Missy Ryan; Editing by Eric Beech)