Jimmy Lai, pro-democracy tycoon, who is standing up to China for Hong Kong

A rags-to-riches millionaire, media tycoon Jimmy Lai is a self-styled "troublemaker" who has been a thorn in Beijing's side for decades thanks to his caustic tabloids and unapologetic support for democracy.

Lai's arrest on Monday under a new national security law Beijing imposed on Hong Kong will come as little surprise to observers, including the publisher himself, who said he knew he would be a prime target.

"I'm prepared for prison," the 71-year-old told AFP from the offices of Next Digital, Hong Kong's largest and most rambunctiously pro-democracy media group, in an interview two weeks before the security law was enacted on 30 June. "If it comes, I will have the opportunity to read books I haven't read. The only thing I can do is to be positive."

Few Hong Kongers generate the level of vitriol from Beijing that Lai does. For many residents of the semi-autonomous city, he is an unlikely hero -- a pugnacious, self-made tabloid owner and the only tycoon willing to criticise Beijing.

But in China's state media he is a "traitor", the biggest "black hand" behind last year's huge pro-democracy protests and the head of a new "Gang of Four" conspiring with foreign nations to undermine the motherland.

Like many of Hong Kong's tycoons, Lai rose from poverty. He was born in mainland China's Guangdong province into a wealthy family but they lost it all when the communists took power in 1949.vSmuggled into Hong Kong aged 12, Lai toiled in sweatshops, taught himself English and eventually founded the hugely successful Giordano clothing empire.