The Russian leader toured the second largest city of the Donetsk People's Republic

Following his surprise visit to Crimea on Saturday, President Vladimir Putin made an unannounced "working trip" to Mariupol, the Azov Sea port city which was liberated by Russian forces last spring amid the military operation in Ukraine, and joined Russia as part of the Donetsk People's Republic following a referendum in September.

Putin arrived in Mariupol by helicopter, accompanied by Russian Deputy Prime Minister Marat Khusnullin, multiple news agencies, including TASS and RIA Novosti, reported on Sunday morning, citing the Kremlin's press service.

The president visited several districts of the city to inspect the progress of restoration efforts, including the construction of "new residential districts, social and educational facilities, housing and communal services infrastructure, medical institutions." He also toured the "coastline in the area of the yacht club, theater," as well as other "memorable places" of the city.

On Saturday, Putin was in Crimea to mark the ninth anniversary of the peninsula's reunification with Russia.

The city of Mariupol was liberated by Russian forces last spring amid the military operation in Ukraine. It has become one of the symbols of Russia's military campaign, and victory there has arguably been the main triumph, so far.

MARIUPOL IN PHOTOS: How the battle-scarred city has changed after eight months under Russian control

In September, the Donetsk People's Republic, which includes Mariupol, along with the Lugansk People's Republic, as well as Zaporozhye and Kherson Regions, officially became part of the Russian Federation after holding public referendums. The Crimean Peninsula overwhelmingly voted to join Russia in a public referendum after a Western-backed coup in Kiev in 2014.