Kim, president of the Presidium of the North's Supreme People's Assembly, headed for Beijing aboard a Chinese flight at Moscow's Sheremetyevo International Airport at about 11:30 p.m. to return home.

After arriving in Moscow via Beijing on Tuesday night, he attended a concert the following day to mark the opening of World Cup, along with Russian President Vladimir Putin and envoys from other countries, and the opening ceremony two days later.

Before the opening ceremony, Kim paid a visit to Putin to deliver a personal letter from North Korean leader Kim Jong-un. The content of the letter was not made public.

Kim Yong-nam and Putin are believed to have exchanged opinions on the result of the historic summit between U.S. President Donald Trump and Kim Jong-un earlier this week in Singapore. Kim asked for Russia's full support in future negotiations on the denuclearization of the Korean Peninsula.

Putin, during the meeting, once again asked Kim Jong-un to visit Russia in September or later.

The Russian leader earlier sent an invitation for Kim to visit Russia through Russian foreign minister Sergei Lavrov when Lavrov met with the North Korean leader during a trip to Pyongyang last month.

The World Cup runs from June 14 to July 15 in 11 Russian cities, including Moscow, St. Petersburg and Nizhny Novgorod.

Although North Korea were eliminated in the Asian qualifying process, Pyongyang sent Kim Yong-nam to the opening ceremony to maintain its friendship with Russia. (Yonhap)