North Korea's Kim Jong Un expressed his "heartfelt thanks" to President Vladimir Putin, state media said Monday, as he headed home after nearly a week in Russia on a defence-focused trip.

Kim's tour of Russia's Far East, which began Tuesday, has showcased potential military ties, with North Korea's leader inspecting everything from Russian space rockets to submarines, and including a symbolic exchange of rifles with Putin

The trip has fanned Western fears that the isolated, nuclear-armed country could provide Moscow with weapons for its assault on Ukraine.

Pyongyang's Korean Central News Agency on Monday said Kim "extended his heartfelt thanks to President Putin and the Russian leadership" for "their special care and cordial hospitality" as he wrapped up the visit.

He also wished "Russia prosperity and its people well-being", the KCNA report added.

North Korea and Russia, historic allies, are both under rafts of global sanctions -- Moscow for its Ukraine offensive, Pyongyang for its nuclear weapon tests.

During his tour to Russia, Kim said his country -- which has Beijing as its most crucial ally and economic benefactor -- would make bilateral ties with Moscow its "number one priority", as he held a rare summit with Putin.

Russia is eager for North Korea's stockpile of artillery shells to be used in Ukraine, while Pyongyang is looking for help with satellite technology and upgrading its Soviet-era military equipment, experts say.

On Wednesday, Putin and Kim held talks at Russia's new Vostochny cosmodrome, roughly 8,000 kilometres (5,000 miles) from Moscow.

After the meeting Putin talked up the prospect of greater cooperation with North Korea and the "possibilities" for military ties.

But the Kremlin has said no agreement has or will be signed.

Kim's latest visit to Russia will "shine long in history", KCNA said, and will further consolidate the two countries' "militant unity" while "opening up a new chapter" of their relations.

While meeting Kim, Putin accepted an invitation to visit North Korea and offered to send one of its nationals to space, which would be a first.

Kim is heading back to North Korea by bulletproof train, with KCNA saying the leader "starts his way home after bringing about a new radical turn in the history of the development of the DPRK-Russia relations."  

DPRK is the acronym for North Korea's official name.

Before departing from Vladivostok, the Pacific port city just over the border, Kim was presented with five explosive drones, a reconnaissance drone and a bulletproof vest as gifts from the governor of the Primorye region, which borders China and North Korea.

cdl/ceb/sn/ssy