BEIJING/TAIPEI (Reuters) -- China warned Lithuania on Tuesday not to "send the wrong signals to Taiwan independence forces" after the Chinese-claimed island said it would open a de facto embassy in the Baltic country, a move the United States strongly backed.
Beijing considers the democratically-governed island to be part of "one China", and it is the country's most sensitive territorial issue.
China's Taiwan Affairs Office said it opposed any country with which it maintains diplomatic ties having official relations with Taiwan.
"We urge Lithuania to abide by the one-China principle and not to send the wrong signals to Taiwan independence forces," it said in a statement.
Lithuania said earlier this year it plans to open its own representative office in Taiwan, a decision that also angered Beijing. The country announced last month it would donate 20,000 COVID-19 vaccine doses to Taiwan.
Taiwan Foreign Minister Joseph Wu said the new mission in Vilnius would be called the Taiwanese Representative Office in Lithuania, the first time the island's name has been used for one of its offices in Europe, as normally only "Taipei" is used.
"Taiwan and Lithuania are both at the strategic forefront of defending democratic institutions," Wu said.
"I believe that through the close connection of shared values, the two countries' peoples can work together to play a positive role in the international community and contribute to world peace, stability and prosperity."
The United States welcomed the move, with its de facto embassy in Taiwan saying: "All countries should be free to pursue closer ties and greater cooperation with Taiwan, a leading democracy, a major economy, and a force for good in the world".
Only 15 countries have formal diplomatic ties with Taiwan, but many others have de facto embassies which are often termed trade offices, as is the case for the European Union, of which Lithuania is a member state.
China has ramped up pressure on countries not to engage with Taiwan.
In February, the South American country of Guyana revoked a deal for Taiwan to open a representative office there only a day after Taipei had announced it. Taiwan blamed Chinese "bullying" for the decision.