WASHINGTON - A key U.S. lawmaker is warning China against harsh reprisals on pro-democracy protestors in Hong Kong, thousands of whom occupied the territory's international airport on Monday, forcing the cancellation of all flights.

"The people of Hong Kong are bravely standing up to the Chinese Communist Party as Beijing tries to encroach on their autonomy and freedom, " Senate Republican Majority Leader Mitch McConnell said on Twitter. "Any violent crackdown would be completely unacceptable."

"As I have said on the Senate floor: The world is watching," McConnell said.

The people of Hong Kong are bravely standing up to the Chinese Communist Party as Beijing tries to encroach on their autonomy and freedom. Any violent crackdown would be completely unacceptable. As I have said on the Senate floor: The world is watching. https://t.co/5VPm5P4PfB — Leader McConnell (@senatemajldr) August 12, 2019

There was no violence reported at the airport, one of the world's busiest, but dozens of injuries were reported on Hong Kong's streets, where angry protesters blocked roads and refused police orders to disperse after riot officers fired tear gas and non-lethal ammunition at fleeing crowds.

China on Monday termed the protests "terrorism."

McConnell, a political ally of President Donald Trump, has taken a stronger public stance against the treatment of the demonstrators in Hong Kong, a Chinese territory, than the U.S. leader.

Last month, in a speech to the Senate, McConnell attacked China's treatment of the Hong Kong demonstrators, saying, "Increasingly brutal police tactics and pro-Mainland vigilantes are drawing blood in an effort to intimidate Hong Kongers back into submission."

FILE - Anti-extradition bill protesters attend a mass demonstration at Hong Kong International Airport, Aug. 12, 2019.

He added, "The world is watching and wondering: If a government cannot respect the basic rights of people it claims as its own citizens, why on Earth would it be trusted to respect the rights and interests of its neighbors, its trading partners, or the companies that invest in its economy?"

Trump has imposed tariffs on hundreds of billions of dollars of Chinese exports to the U.S. and attacked Beijing's unwillingness to reach agreement on a trade deal with the U.S. But he has adopted a hands-off stance on Beijing's treatment of the Hong Kong protesters.

"I don’t know what China’s attitude is," Trump told reporters last week. "Somebody said that at some point they’re going to want to stop that. But that’s between Hong Kong and that’s between China, because Hong Kong is a part of China. They’ll have to deal with that themselves. They don’t need advice.”