The Chinese flag flies at a plaza near the Potala Palace in Lhasa in western China's Tibet Autonomous Region, June 1, 2021, as seen during a government organized visit for foreign journalists. (File Photo - AP)

China on Monday condemned Lithuania’s expulsion of three Chinese diplomats as relations between the two countries continue to sour.

A Chinese Foreign Ministry spokesperson accused Lithuania of expelling its diplomats and declaring them persona non grata “without any reason,” according to a statement posted on the ministry’s website.

“China strongly condemns and firmly rejects this wanton and provocative action,” the spokesperson said.

The spat comes amid an investigation into the suspected involvement of a Chinese ship in severing two undersea data cables, one of which runs under the Baltic Sea between Lithuania and Sweden.

Sweden has asked China to cooperate in explaining the cables’ rupture.

Lithuania on Friday announced it had notified Beijing of declaring “three members of the non-accredited staff” of China’s diplomatic mission persona non grata, and that they had to leave the Baltic nation within a week.

The Lithuanian Foreign Ministry did not specify who the people were or what they had done but cited provisions of the Vienna Convention on Diplomatic Relations and other international laws.

When asked to clarify what had happened, the Lithuanian Foreign Ministry referred The Associated Press to its original notice.

It added the presence of several other staff members of China’s diplomatic mission in Lithuania would be decided “in the near future.”

The Chinese Foreign Ministry spokesperson accused Lithuania of having “again taken detrimental action that further exacerbates the relations.”

“China calls on Lithuania to immediately stop undermining China’s sovereignty and territorial integrity, and stop creating difficulty for bilateral relations,” the spokesperson said, adding that Beijing reserved the right to take countermeasures.

Neither foreign ministry made specific reference to the Chinese ship in the Baltic.

The dispute comes three years after China downgraded ties with Lithuania to below ambassador level in retaliation for the Baltic nation allowing Taiwan, the island democracy claimed by Beijing as part of its territory, to open a representative office.

China regards Taiwan as a breakaway province and prohibits other countries from having formal ties with Taipei. (AP)