US Secretary of State Mike Pompeo on Tuesday vowed to protect Hong Kong pro-democracy campaigners who have fled the city and denounced China after Beijing said that police had ordered the arrests of overseas activists. "The Chinese Communist Party cannot tolerate the free thinking of its own people, and increasingly is trying to extend its reach outside China's borders," Pompeo said in a statement. "The United States and other free nations will continue to protect our peoples from the long arm of Beijing's authoritarianism." In an accompanying tweet, Pompeo said that Washington "condemns the Chinese Communist Party's attempt to prosecute pro-democracy advocates resident outside of China, including in the United States." Chinese state media said late Friday that Hong Kong police had ordered the arrest of six pro-democracy activists living in exile on suspicion of violating a tough new security law. One of them, Samuel Chu, head of the Washington-based Hong Kong Democracy Council, wrote on Twitter that he has been a US citizen for 25 years. The most prominent person targeted was 27-year-old campaigner Nathan Law, who recently fled Hong Kong for Britain and called the charges against him "trumped up." Hong Kong police refused to comment on the charges. But China's ambassador to the United States, Cui Tiankai, appeared to confirm and defend the charges. "All these law enforcement actions are taken according to the law," Cui said in response to a question at the Aspen Security Forum. "Anybody, if they violate the law, they should be punished. That's it. It doesn't matter what kind of political views they might have." China in late June passed a security law that bans subversion and other perceived offenses in the financial hub, sending a chill through a city that witnessed wide and occasionally destructive pro-democracy protests last year. The United States has denounced the law and said it would end special treatment for Hong Kong, to which Beijing promised freedoms before Britain handed back the territory in 1997.