Reuters reports that China's Foreign Ministry said that U.S. officials who have engaged in "nasty" behaviour over Chinese-claimed Taiwan will face sanctions after Washington lifted curbs on exchanges between U.S. and Taiwanese officials.

Ties have worsened as China has already condemned this month's easing, announced by U.S. Secretary of State Mike Pompeo in the waning days of President Donald Trump's presidency.

Further adding to China's anger, the U.S. ambassador to the United Nations, Kelly Craft, spoke last week to Taiwan President Tsai Ing-wen, after a planned trip to Taipei was called off.

Asked at a daily news briefing how China would follow through on its pledge to make the United States "pay a heavy price" for its engagements with Taiwan, ministry spokeswoman Hua Chunying said some U.S. officials would face sanctions.