Jimmy Lai, the pro-democracy former Hong Kong media tycoon and a fierce critic of Beijing, has been sentenced to 20 years in prison in one of the most prominent cases prosecuted under a China-imposed national security law.

A Hong Kong court moved closer to sentencing prominent democracy advocate Jimmy Lai, who was convicted under a national security law and could face up to life imprisonment.

A Hong Kong court on Monday heard arguments about the sentence for pro-democracy media founder Jimmy Lai in a landmark national security case.

Hong Kong pro-democracy newspaper Apple Daily has increased its print run more than fivefold to 500,000 copies as residents lined up to buy the paper in a show of support for beleaguered press freedoms, a day after police arrested five top editors and executives.

Hong Kong police have used a sweeping national security law to arrest five editors and executives of a pro-democracy newspaper on charges of colluding with foreign powers.