The world has been "uncertain" since the outbreak of the Ukraine war, and there are concerns about the implications Russia's actions hold for world security, Australian Prime Minister Anthony Albanese said Sunday before departing to Spain for an "absolutely critical" NATO summit in Madrid.

The leaders of Australia, New Zealand, Japan, and South Korea have been invited to the summit expected to mostly discuss the Ukraine war.

"The Russian invasion of Ukraine has upset the norms that we regarded - that the rule of law would be maintained, that sovereign nation's borders would be respected and that we wouldn't see the sort of brutal invasion that we've seen from Russia in Ukraine," he said.

Speaking about Russia's close ties with Russia and Moscow's own actions, Albanese said the security in the world and the Indo-Pacific region have been jeopardized. 

"Russia and China, their arrangements and closeness that has occurred in recent times means that it's also very important for our region," he said.

"The people of Ukraine are doing the democratic world, an enormous service," he claimed. "But it's important that democratic nations stand with Ukraine. That's the context of this NATO Summit."

Albanese is set to land in the Spanish capital today, and he has a full week of bilats planned for his stay in Europe, including talks with US President Joe Biden and top EU leaders.

"I look forward to attending the NATO Summit and contributing," Albanese said.

On his invitation to visit Ukraine by President Volodymyr Zelensky, Albanese said he wants to make sure it is safe to visit the country before doing so.

"It certainly is appreciated, the fact that President Zelenskyy has made this invitation to Australia, and we regard it as a good thing if it's able to be undertaken," he said.

Ahead of Albanese's visit, thousands of people took to the streets all over Madrid, carrying the former Soviet Union's hammer and sickle flags to protest the NATO summit scheduled in the Spanish capital.

Leaders of member countries will meet in Madrid on June 29-30, amid tight security, as the organization faces the unprecedented challenge of the war in Ukraine.

"Tanks yes, but of beer with tapas," sang demonstrators, who claimed that an increase in European defense spending advocated by NATO was a threat to peace.

Spain's Foreign Minister Jose Manuel Albares said in a newspaper interview published on Sunday that the summit would also focus on the threat from Europe's southern flank in Africa, in which he said, "Russia posed a threat to Europe."

Read next: NATO members have declined Kiev's aspirations: Zelensky's office