The Chinese foreign ministry said on Monday it was in touch with Prague over President-elect Petr Pavel's scheduled call with Taiwan's President Tsai Ing-Wen.
Pavel is due to speak with Tsai on Monday, Pavel's spokeswoman said, a highly unusual move given the lack of formal ties and a diplomatic coup for Taipei that is likely to anger China.
China claims the self-ruled island of Taiwan as a province and most countries' leaders avoid high-level public interactions with Taiwan and its president, not wishing to provoke China, the world's second largest economy.
In Beijing's first response to what could become a full-blown diplomatic row with Prague, the Chinese foreign ministry said Pavel had previously said during his election campaign that the One-China Principle should be respected, according to a statement sent to Reuters.
"The Chinese side...is currently seeking verification with the Czech side, (we) hope the Czech side strictly upholds the One-China Principle," the foreign ministry said.
(Reporting by Eduardo Baptista, editing by Ed Osmond)