WRAPUP 2-Firebrand democrats poll strongly in HK, election organiser quits over Beijing pressure

* Young firebrand activists poll strongly

* Beijing warns primaries may violate security law

* Pro-democracy poll organiser quits

* Trump ends Hong Kong's special status

* New York Times moves staff from Hong Kong to Seoul

By Jessie Pang and Yanni Chow

HONG KONG, July 15 (Reuters) - Young firebrand activists polled strongly in Hong Kong pro-democracy primaries in initial results released on Wednesday, but one election organiser stepped down after Beijing warned the vote may violate a new national security law.

Former democracy lawmaker Au Nok-hin helped organise the weekend poll that saw more than 610,000 people vote in what was widely seen as a symbolic protest against the sweeping legislation imposed on the city by Beijing.

"Withdrawal is the only choice (I have, to) ... protect myself and others," Au said in a Facebook post.

The primary polls were aimed at selecting democracy candidates to stand in September elections for the Legislative Council, Hong Kong's governing body.

Results from the primaries so far show 16 candidates from the "resistance" or "localist" camps were elected, outshining the traditional democrats who secured 12 votes.

The strong performance of the younger generation reflects a potential change of guard to a more radical grouping likely to rile authorities in Beijing.

The remaining results are expected later on Wednesday.

Some voters are frustrated with Hong Kong's more moderate traditional democracy groups at a time when Beijing is tightening its grip on the city with a new security legislation seen by many as the latest attempt to crush freedoms.

The democrats are gearing up for elections on Sept. 6, when they hope to secure a majority in the 70-seat legislature for the first time.

In comments that critics said were aimed at instilling fear in the community, Beijing's top office in the city, the Hong Kong Liaison Office, the Chinese government agency Hong Kong and Macau Affairs Office, and the city's leader Carrie Lam have all said the primaries could violate the new national security law.

While a spokesman for the Liaison Office said the pro-democracy camp's bid for a legislative majority was an attempt to carry out a 'color revolution' in Hong Kong, referring to populist uprising in other parts of the world.

"For those who do not recognise democracy, or do not agree with democratic values, it is difficult to understand the meaning of the primary election," said Benny Tai, another organiser of the pro-democracy polls.

The new security law punishes what Beijing broadly defines as secession, subversion, terrorism and collusion with foreign forces with up to life in prison and sees Chinese intelligence agents operating officially in the city for the first time.

Critics of the law fear it will crush wide-ranging freedoms promised to Hong Kong when it returned to Chinese rule in 1997, while supporters say it will bring stability to the city after a year of sometimes violent anti-government protests.

Hong Kong police on Wednesday arrested the vice chairman of the city's Democratic Party, Lo Kin-hei, on charges of unlawful assembly related to anti-government protests in November, he wrote on his Facebook page. He was released on bail.

Hong Kong police said they charged five males aged 21 to 70 with unlawful assembly, without giving names and they will be mentioned in court on Aug. 21.

The moves come as U.S. President Donald Trump on Tuesday ordered an end to Hong Kong's special status under U.S. law to punish China for what he called "oppressive actions" against the former British colony.

"Hong Kong will now be treated the same as mainland China," Trump said.

China said on Wednesday it would impose retaliatory sanctions on U.S. individuals and entities after Trump signed a law penalising banks doing business with Chinese officials who implement the new Hong Kong national security law.

In another blow to the city's international status, the New York Times said it would shift part of its Hong Kong office to Seoul, as worries grow that security law would curb media and other freedoms in the city. (Additional reporting by Aleksander Solum; Writing by Farah Master and Anne Marie Roantree; Editing by Michael Perry)