Poland has called for deployment of peacekeeping mission to supply humanitarian aid to Ukraine amid Moscow attacks against Kiev.

Jaroslaw Kaczynski, Poland's deputy prime minister, who is considered the main strategist of government policy, made the plea during a visit to Ukraine on Tuesday, after he and the prime ministers of the Czech Republic, Poland, and Slovenia arrived in the capital city of Kiev in a show of high-level support for the ex-Soviet country on behalf of the European Union.

"I think that we need a peacekeeping mission from NATO, or even possibly from a larger international structure, but a mission that will be able to defend itself and that will operate on Ukrainian territory, which will be in this country with the agreement of the president and the government of Ukraine and it will not be a defenseless mission," Kaczynski said.

"It will be a mission that will strive for peace, to provide humanitarian aid, but at the same time it will also be protected by appropriate forces, armed forces," he added.

Polish Prime Minister Mateusz Morawiecki also called on the EU to "very quickly give Ukraine candidate status," adding, "We will try to organize defensive weapons."

The premiers of the Czech Republic, Poland, and Slovenia, who traveled to Kiev by train on Tuesday, were the first foreign leaders to visit Ukraine since Russia's offensive began last month. According to a statement posted on the Polish government's website, the purpose of the European leaders' visit is to "confirm the unequivocal support of the entire European Union for the sovereignty and independence of Ukraine and to present a broad package of support for the Ukrainian state and society."

The idea of the trip had been agreed at an EU leaders' summit in France last week.

Shortly after their arrival, Ukraine's deputy prime minister praised "the courage of the true friends of Ukraine." Ukrainian President Volodymyr Zelensky also thanked the visiting European leaders for their support at a news conference.

"We absolutely trust these countries and the leaders of these countries… we are 100% sure that everything we discuss will achieve its goals for our country, our security and our future," he said.

The latest development comes as Russian forces are making advances toward the Ukrainian capital in an attempt to besiege the city, which has been put under curfew.

Russian President Vladimir Putin announced a "special military operation" in Ukraine on February 24. The conflict has provoked a unanimous response from Western countries, which have imposed a long list of sanctions on Moscow.

Russia says it will halt the military operation instantly if Kiev meets certain demands, including that Ukraine never join NATO.

Meanwhile, Zelensky has provided a more optimistic view of the positions of Russia at peace talks, saying they are becoming "more realistic" but adding that more time is needed.

"The meetings continue, and, I am informed, the positions during the negotiations already sound more realistic. But time is still needed for the decisions to be in the interests of Ukraine," he said in a video address released early on Wednesday.

The talks were expected to resume later in the day, with senior Ukrainian negotiator Mykhailo Podolyak saying talks with Russia were very difficult but there was "certainly room for compromise."

Negotiators from the two sides have held several rounds of talks since last month. The talks have led to the opening of several humanitarian corridors to evacuate civilians from combat areas. But both sides have accused each other of blocking those efforts.

Earlier this week, Turkey hosted a first face-to-face meeting between the Russian and Ukrainian foreign ministers in an attempt to de-escalate tensions, which yielded no results.

The fourth round of the talks between Russia and Ukraine resumed on Monday, after both sides hailed progress in earlier rounds despite no significant breakthrough.