A naturalized American citizen and pastor's son has been charged with "inciting secession" and "colluding with foreign powers" under Hong Kong's new national security law. 

Samuel Chu is a pro-democracy activist and managing director of the Hong Kong Democracy Council, based in Washington DC. 

A warrant for the arrest of the activist, who is now in Los Angeles, has been issued by Hong Kong police, NBC News reports. 

Other activists charged under the national security law are Nathan Law, Wayne Chan Ka-kui, Honcques Laus, Simon Cheng and Ray Wong Toi-yeung. 

Writing in the New York Times, Chu warned that no one was beyond the law's reach. 

"It doesn't matter that I've been an American citizen for 25 years — having left Hong Kong in 1990 to live in the United States," he said.

"I had violated Article 38 of the new law, which states: 'This Law shall apply to offenses under this Law committed against the Hong Kong Special Administrative Region from outside the Region by a person who is not a permanent resident of the Region'.

"In other words, every provision of this law — which was concocted in Beijing and enacted without the Hong Kong legislature — applies to everyone outside of Hong Kong.

"Nobody is beyond the law's reach, not me in the United States, and certainly not the estimated 85,000 Americans living and working in Hong Kong itself," he warned.

Chu's father is the Rev Chu Yiu-ming, who co-founded Occupy Central, a non-violent civil disobedience campaign in 2014 calling for a democratic electoral system. 

He was last year convicted by a Hong Kong court over his involvement in the campaign, and given a suspended sentence. 

There has been strong international condemnation of the national security law, with Christians fearing that it may infringe on religious freedoms and lead to persecution. 

Earlier this month, the Methodist Church in Britain called on HSBC to re-think its support for the controversial law, which is aimed at cracking down on dissent in the territory. 

Hong Kong Cardinal Joseph Zen, who has often criticised Beijing, has said he is prepared to be arrested.

"I shall be prudent; I do not seek to offend, but when I deem it necessary, I will say it," said the 88-year-old.

"If such right and proper words are considered to be against their law, I will endure all the suing, trials and arrests. Numerous predecessors have endured similarly. We have seen how God has always helped them."