North Korea's top diplomat said her country is "ready to greet" Russian President Vladimir Putin, state media reported Sunday, in the latest sign of deepening ties between the two authoritarian states.

Traditional allies Russia and North Korea have recently boosted ties, with Pyongyang's leader Kim Jong Un making a rare overseas trip to meet Putin in Russia's Far East last September.

The West has accused Moscow and Pyongyang of working together to support Russia's invasion of Ukraine, with North Korea believed to have sent hundreds of thousands of artillery shells and weapons to its ally.

North Korean foreign minister Choe Son Hui was in Moscow last week for meetings with Putin and her Russian counterpart Sergei Lavrov.

The North Korean "government warmly welcomes President Putin to visit Pyongyang and is ready to greet the Korean people's closest friend with the greatest sincerity," Choe told Putin, according to a statement from the foreign minister's assistant office, carried by the Korean Central News Agency.

Putin expressed "his willingness to visit the DPRK at an early date", the statement said, referring to the North's official name, the Democratic People's Republic of Korea.

The statement added that Russia had expressed "deep thanks... for extending full support and solidarity to the stand of the Russian government and people on the special military operation in Ukraine."

Increasing military and economic cooperation between Russia and North Korea has triggered concerns in Washington and Seoul.

Top Russian officials, including Moscow's defence and foreign ministers, visited North Korea last year, fanning concern among Kyiv's allies over a potential arms deal.

This month, the White House accused Pyongyang of sending ballistic missiles and launchers to Russia in what it called a "significant and concerning escalation" of support for Moscow's war effort.

South Korea has accused Pyongyang of having provided more than one million artillery rounds to Moscow in exchange for advice on military satellite technology.

North Korea succeeded in putting a spy satellite into orbit last year, with Seoul saying it received Russian help.