The U.N.'s special envoy for Syria says Syrian President Bashar Assad remains part of the equation for ending the nearly four-year conflict.

Staffan de Mistura says he met with Assad recently and "will continue having very important discussions with him because he is part also of the solution."

Mistura spoke Friday after meeting with Austrian Foreign Minister Sebastian Kurz. The envoy said only the Islamic State extremist group benefits from the Syrian war.

The violence has claimed more than 220,000 lives, according to United Nations estimates.