Warsaw has emerged as a key buyer of arms from Seoul, and the countries signed a weapons deal worth over $40 billion in 2022.

Polish Prime Minister Donald Tusk is in Seoul for the first such visit in 27 years, and held a summit with South Korean President Lee Jae Myung on Monday.

"Mutually beneficial defence cooperation between the two countries will be further expanded," Lee told a joint press conference afterwards.

He stressed the "steady implementation" of the 2022 agreement, calling it "essential for deepening and advancing our defence industry cooperation".

Under the deal, Poland has bought South Korean military hardware including tanks, self-propelled howitzers and rocket launchers.

Some of those weapons are now "operating proudly across Poland's vast plains, helping to safeguard the country's territory and protect its people", Lee said in his opening remarks before the summit.

Seoul and Warsaw would elevate ties to a "comprehensive strategic partnership", he added.

Poland, a member of the European Union and the NATO defence bloc, has stood firmly behind neighbouring Ukraine since Russia launched its full-scale invasion in February 2022.

South Korea has backed Kyiv, especially since North Korea deployed troops to support Russia, but has stopped short of supplying lethal weapons, citing a domestic ban on militarily aiding countries at war.

Tusk described South Korea as "Poland's second-most important ally after the United States", according to a Korean translation of his opening remarks.

Defence cooperation "remains the core driving force of bilateral relations", he said, adding that Warsaw would encourage South Korean partner firms to shift production lines to Poland.

The two leaders also agreed to expand cooperation in non-defence fields, including energy supply chains and infrastructure.

Tusk wraps up his visit on Monday and will then head to Tokyo.