Putin's remarks came during his 12th annual news conference, which more than 1,400 journalists attended. 

Speaking in a broadcast carried on state-owned channel RT, Putin said: "This is the biggest operation in the world."

Putin claimed about 100,000 people had been evacuated from Aleppo. 

The Russian leader also described trilateral cooperation between Turkey, Iran and Russia as playing a “critical role” in the Aleppo crisis.

A meeting of Russian, Iranian and Turkish foreign ministers was held on Tuesday in Moscow. They agreed on a joint declaration to ensure the evacuation of civilians and armed groups from eastern Aleppo.

Putin said this could not have been achieved without the "active" cooperation of Turkey and Iran. 

Russia’s president said there was a need to sign a cease-fire deal in Syria. He recalled that Turkey and Iran had agreed on an earlier suggestion to bring together representatives of the Syrian regime and opposition in Kazakhstan. 

Kazakhstan President Nursultan Nazarbayev had expressed his "readiness" to provide a platform for talks in Astana.