China has repeatedly said the Taiwan question concerns China's core interests.
When asked if China has overreacted to the senator's Taiwan visit, Wang said such behavior seriously interferes in China's domestic affairs, reiterating that there's only one China and Taiwan is a part of China.
Adhering to the one-China principle is the foundation of China's diplomatic relations with other countries including the Czech Republic, he continued, and adhering to the principle is also the Czech Republic's political promise to China.
The senator speaker made the visit despite China's opposition, and publicly supported "Taiwan independence," which is a "public affront," Wang said.
"We have to tell the Czech Senate speaker: You've crossed the line."
Earlier on Tuesday, Chinese Foreign Ministry spokeswoman Hua Chunying said Vystrcil was openly supporting separatism and interfering in China's internal affairs. "China strongly condemns this," Hua told reporters.
Chinese Vice Foreign Minister Qin Gang and the Chinese Embassy in the Czech Republic have also lodged solemn representations with the Czech Embassy in China and the Czech Foreign Ministry.
(Cover: China's State Councilor and Foreign Minister Wang Yi gestures as he meets with Canada's Foreign Minister Francois-Philippe Champagne (not pictured) in Rome, Italy, August 25, 2020. /Reuters)