President Xi Jinping on Thursday sent a message of condolence to Russian President Vladimir Putin over the recent crash of a passenger plane.

In his message, Xi said he was shocked to learn about Tuesday's crash in the Kamchatka Territory in the Far East.

The 28 people on board included six crew members and 22 passengers, including two minors. All were presumed dead.

On behalf of the Chinese government and its people and in his own name, Xi expressed profound condolences over the deaths and conveyed sincere sympathies to the bereaved families.

The An-26 plane flying from Kamchatka's main city of Petropavlovsk-Kamchatsky to the coastal town of Palana with 28 people on board disappeared and crashed.

A search team on Wednesday found the remains of 19 people. Rescuers later on Tuesday found wreckage of the plane near Palana after it was believed to have flown into a cliff.

Kamchatka is a vast peninsula popular with adventurous tourists for its abundant wildlife, live volcanoes and black sand beaches.

Governor Vladimir Solodov declared a three-day mourning period beginning on Wednesday and said families of the victims would receive 3.5 million rubles ($47,000).

In Palana, Solodov said authorities would "do everything to help them live through this tragedy".

In a telegram to the Kamchatka governor, Putin expressed his condolences.

Officials have said the plane－built in 1982－was in good condition and passed safety checks.

Russia's Investigative Committee, which probes major crimes and incidents, said it was looking at three potential causes of the accident: poor weather conditions, technical malfunctions, or pilot error.

Mo Jingxi in Beijing, agencies and Xinhua contributed to this story.