Ukrainian President Volodymyr Zelensky said Saturday it was "extremely important" for Kyiv to maintain friendly ties with neighbouring Poland, where incoming nationalist leader Karol Nawrocki opposes Ukraine's NATO bid.

Nawrocki won Poland's presidential election this month after a campaign in which he criticised Ukraine and accused Zelensky of "indecent" behaviour towards his allies.

Poland is one of Ukraine's closest allies and has served as a crucial logistics hub for Western military aid to help Kyiv's war effort against Russia's now more than three-year-long invasion.

Zelensky hosted outgoing Polish President Andrzej Duda in Kyiv on Saturday, ahead of Nawrocki's inauguration on August 6.

"Poland is now preparing for the inauguration of its new president, (Karol) Nawrocki,"Zelensky told reporters alongside Duda.

"We will do everything in our power to ensure that relations between our countries only grow stronger."

He added it was "extremely important" to preserve mutual support and understanding between the two nations.

Poland has taken in over a million Ukrainians since Russia's invasion of the country began in 2022.

But anti-Ukrainian sentiment has grown in recent years, intensifying during the election campaign.

In May, Nawrocki said Ukraine "has not shown gratitude for what Poles have done" and accused Zelensky of "insolence".

While pledging to back Ukraine's war effort, Nawrocki has criticised some of the support measures granted to Ukrainian refugees.

Duda said he believed Nawrocki would "build the best possible neighbourly relations" for the future of both countries.

"From behind the president's desk, the world looks a little different than... especially from the position of a candidate in the elections," Duda said when asked about Nawrocki's future ties with Ukraine.