The rift between China and Taiwan has crossed  the shores to Vilnius, capital of Lithuania. The diplomatic kerfuffle has acquired a new dimension with China downgrading ties with Lithuania over Taiwan.

After Taiwan opened a representative office in the Lithuanian capital, China brought down the level of relations to the rank of Charge d’Affaires, a notch below the ambassador. China’s foreign ministry said in a statement on Sunday that Lithuania had ignored Beijing’s “solemn stance” and the basic norms of international relations in allowing Taiwan to set up its representative office.

The office, according to China “openly creates the false impression of ‘one China, one Taiwan’ in the world, renounces the political commitment made by Lithuania … on the establishment of diplomatic relations with the People’s Republic of China, undermines China’s sovereignty and territorial integrity, and grossly interferes in China’s internal affairs.”

China views self-ruled and democratically governed Taiwan as its own territory with no right to the trappings of a state and had earlier expelled the Lithuanian ambassador in protest against growing ties between Vilnius and Taipei. The move has created a “bad precedent internationally”, Beijing said, adding that relations would be downgraded.

“We urge the Lithuanian side to correct its mistakes immediately and not to underestimate the Chinese people’s firm determination and staunch resolve to defend national sovereignty and territorial integrity.” No matter what Taiwan does, it cannot change the fact that it is part of China, the ministry added.

Lithuania’s foreign ministry has said it “regrets” China’s decision. “Lithuania reaffirms its adherence to the ‘One China’ policy, but at the same time has the right to expand cooperation with Taiwan,” the ministry said in a statement. Other Taiwan offices in Europe and the United States of America use the name of the city Taipei, avoiding a reference to the island itself, something that has further angered Beijing.

Taiwan says it is an independent country called the Republic of China, its official name, and that the People’s Republic of China has never ruled it and has no right to speak for it. Taiwan has been heartened by growing international support for it, especially from the US and some of its allies, in the face of Beijing’s military and diplomatic pressure. Washington has offered Vilnius support to withstand Chinese pressure, and Lithuania will sign a $600m export credit agreement with the US Export-Import Bank this week.

Only 15 countries have formal diplomatic ties with Taiwan. The other player with skin in the game is the European Union, which had previously warned of an impact on the bloc’s relations with China, should Vilnius’ ties with Beijing deteriorate. The EU says it “does not regard the opening of a representative office in or from Taiwan as a breach of the EU’s One China policy.”

While agreeing that it was a bilateral matter between China and Lithuania, its spokesman said, “the EU has stood by Lithuania in the face of sustained coercive measures from China.”