Ukraine on Sunday condemned what it called "absurd" comments from China's ambassador to France, who questioned the sovereignty of post-Soviet countries.

Speaking Friday on the LCI news channel, ambassador Lu Shaye suggested countries that emerged after the fall of the Soviet Union "don't have effective status under international law because there is not an international agreement confirming their status as sovereign nations."

The comments cast doubt not just on Ukraine, which Russia invaded last February, but all former Soviet republics which emerged as independent nations after the fall of the Soviet Union in 1991, including many members of the European Union.

Ukrainian presidential aide Mykhaylo Podolyak replied on Sunday that the status of post-Soviet countries was "enshrined in international law".

"It is strange to hear an absurd version of the 'history of Crimea' from a representative of a country that is scrupulous about its thousand-year history," Podolyak said, referring to China.

Moscow and Beijing have over the past years ramped up cooperation, and Washington has accused Beijing of mulling arms exports to Moscow -- claims China denied.

Despite strong ties with Russia, China has sought to portray itself as a neutral party in the Ukraine conflict.

It proposed a vague political solution to the conflict.

"If you want to be a major political player, do not parrot the propaganda of Russian outsiders...," Podolyak said.

'Consternation'

A statement issued late Saturday by the French foreign ministry said it had "learned with consternation about the statements from the ambassador".

"It remains up to China to say whether these statements reflect its position which we hope not to be the case," the statement added.

"Remarks by the Chinese Ambassador in France concerning international law and sovereignty of nations are completely unacceptable," Latvia's foreign minister Edgars Rinkevics wrote on Twitter.

"We expect explanation from the Chinese side and complete retraction of this statement."

'Don't trust China'

His Lithuanian counterpart, Gabrielius Landsbergis, added: "If anyone is still wondering why the Baltic States don't trust China to 'broker peace in Ukraine', here's a Chinese ambassador arguing that Crimea is Russian and our countries' borders have no legal basis."

Asked if Crimea was Ukrainian during his interview on LCI, Lu replied, "it depends on how you look at the problem. There's history. Crimea was Russian at the start."

The timing of the controversy is embarrassing for French President Emmanuel Macron who visited Beijing this month to encourage Chinese President Xi Jinping to put pressure on Russian leader Vladimir Putin to end his invasion of Ukraine.

Macron's trip caused unease among some Western allies who are sceptical of China's intentions, given Xi's formal alliance with fellow authoritarian Putin.

Countries that emerged from the break up of the Soviet Union in 1991 were later admitted as sovereign members of the United Nations.