HONG KONG - Shares in a Hong Kong media group critical of Beijing soared more than 300 percent on Monday as democracy activists hit social media urging investors to support the media company after its owner was arrested under the city's new security law.

Jimmy Lai, one of the city's most vocal Beijing critics, and leading executives were arrested in the morning for alleged fraud and colluding with foreign forces -- a newly created national security crime.

Some 200 police officers then raided Next Digital's offices, bringing a handcuffed Lai along with them, in images that were broadcast live by his own employees.

Lai owns the Apple Daily newspaper and Next Magazine, two outlets unapologetically pro-democracy and critical of Beijing.

Along with Lai, his two sons, and four senior management of the media group were also arrested.

The company's share price initially tumbled almost 17 percent but soon rocketed 344 percent to HK$0.40, its highest since June last year. It ended 183 percent higher at HK$0.255.

The spike came after calls went out on Facebook and other social media platforms for people to buy shares.

"The last mainstream media that has been striving to oppose the Communist Party can be over any time," wrote HenryPorterBabel, a Facebook page with more than 39,000 followers, adding it was buying 300,000 shares.

Calls have also gone out online for democracy supporters to buy Tuesday's Apple Daily newspaper -- if it can still be printed.

"I will buy tomorrow's Apple Daily even if it is a pile of blank papers," wrote Shiu Ka-chun, a pro-democracy lawmaker with a photo of him holding a copy of the newspaper.

-- Bloomberg News contributed to this story --

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