European countries are demanding answers from Beijing after its top diplomat in Paris questioned the sovereignty of former Soviet republics, in comments that could undermine China’s efforts to be seen as a potential mediator between Russia and Ukraine.

Officials from Lithuania, Latvia, Ukraine, France and the European Union have all hit back against remarks made by China’s ambassador to France Lu Shaye, who said during a television interview that former Soviet countries, including the Baltic states, don’t have “effective status in international law.”

Lu made the remarks in response to a question whether Crimea, which was illegally annexed by Russia in 2014, was part of Ukraine.

“Even these ex-Soviet countries don’t have an effective status in international law because there was no international agreement to materialize their status as sovereign countries,” Lu said, after first noting that the question of Crimea “depends on how the problem is perceived” as the region was “at the beginning Russian” and then “offered to Ukraine during the Soviet era.”

The remarks appeared to disavow the sovereignty of countries that became independent states and United Nations members after the fall of the Soviet Union in 1991 – and come amid Russia’s brutal invasion of Ukraine under leader Vladimir Putin’s vision the country should be part of Russia.

China has so far refused to condemn Russia’s invasion of Ukraine or call for a withdrawal of its troops, instead urging restraint by “all parties” and accusing NATO of fueling the conflict. It has also continued to deepen diplomatic and economic ties with Moscow.

EU foreign affairs chief Josep Borrell responded Sunday calling the remarks “unacceptable.”

“The EU can only suppose these declarations do not represent China’s official policy,” Borrell said in a statement on Twitter.

France also responded Sunday, with its Foreign Ministry stating its “full solidarity” with all the allied countries affected and calling on China to clarify whether these comments reflect its position, according to Reuters.

Several leaders in former Soviet states, including Ukraine, were quick to hit back following the interview, which aired Friday on French station LCI.

Latvian Foreign Minister Edgars Rinkevics called for an “explanation from the Chinese side and complete retraction of this statement” in a post on Twitter Saturday.

He pledged to raise the issue during a meeting of EU foreign ministers Monday, where relations with China are expected to be discussed.

“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,” Mykhailo Podolyak, an adviser to Ukraine’s Presidential Administration, also wrote on Twitter.

“If you want to be a major political player, do not parrot the propaganda of Russian outsiders…”

China’s Ministry of Foreign Affairs did not immediately respond to a request for comment from CNN on Monday.

This is not the first time that Lu – a prominent voice among China’s so-called aggressive “wolf-warrior” diplomats – has sparked controversy for his views.

Ties have soured as Europe has uneasily watched China’s tightening relationship with Russia and its refusal to condemn Putin’s invasion.

Beijing in recent months has sought to mend its image, highlighting its stated neutrality in the conflict and desire to play a “constructive role” in dialogue and negotiation, further fueling debate in European capitals over how to calibrate its relationship with China, a key economic partner.

“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,” Lithuanian Foreign Minister Gabrielius Landsbergis wrote on Twitter Saturday following Lu’s interview.

Moritz Rudolf, a fellow and research scholar at the Paul Tsai China Center of the Yale Law School in the US, said China had been “increasingly successful in being perceived as a responsible power that might play a constructive role in a peace process in Ukraine.”

“It remains to be seen whether the leadership in Beijing realizes how damaging those words may turn out to be for its ambitions in Europe if the Foreign Ministry does not distance the (People’s Republic of China) from the words of Ambassador Lu,” he said.

He added that China’s “official position and practice” contradict Lu’s comments, including as China had not recognized the sovereignty of Russia over Crimea or any territory it annexed since 2014.

Others suggested Lu’s remarks may also shed light on Beijing’s real diplomatic priorities.

For Russia, giving up control of Crimea is widely seen as a non-starter in any potential peace settlement on Ukraine. This means Beijing may have a hard time giving a straight answer on this question, according to Yun Sun, director of the China Program at the Washington-based think tank Stimson Center.

“The question is impossible to answer for China. China’s relationship with Russia is where its influence comes from,” she said, adding that didn’t mean Lu could have given a “better answer.”

“Between sabotaging China’s relationship with Russia and angering Europe, (Lu) chose the latter.”