A Hong Kong internet radio host was charged on Monday under a little-used colonial-era sedition law that authorities have begun to wield against Beijing's critics.

Officers from the police's national security department charged 52-year-old Wan Yiu-sing with four counts of "seditious intent", according to a court document.

It is the second time the sedition law has been applied since Hong Kong's 1997 handover to China as police use an expanded suite of legal powers to pursue dissidents following huge and often violent democracy protests in 2019.

The charges stem from the content of four online radio shows Wan hosted last year. According to the charge sheet, police accused Wan of trying to "bring into hatred or contempt or to excite disaffection" against the Chinese and Hong Kong governments in his programmes as well as "excite inhabitants" to break the law.

The content of the allegedly seditious shows is not known. But Wan -- better known by his DJ name "Giggs" -- has hosted programmes discussing anti-government demonstrations and calling for donations to support young Hong Kongers who have fled to nearby Taiwan.

Hong Kong's sedition law is separate to a sweeping national security law that Beijing imposed on the city last summer.

It dates back to the mid-19th century during British colonial rule.  The law remained on the books after the handover to China but was never used in a city that had enjoyed political freedoms unseen on the Chinese mainland.

But after 2019's democracy protests, prosecutors dusted it off. Last September, another pro-democracy radio host, Tam Tak-chi, became the first person to be charged with sedition since the handover.

He faces five counts of sedition and is currently in custody awaiting trial. Tam's upcoming trial will be a legal test for how sedition sits with the freedoms of speech supposedly guaranteed by Hong Kong's mini-constitution and its bill of rights.

It will also be closely monitored by those concerned that Hong Kong's place as a regional bastion of press freedom could be over.

Beijing's national security law has begun peeling back many liberties.

It has quashed protests and effectively outlawed a host of peaceful political views, including advocating for independence, greater autonomy or full democracy in Hong Kong.

Wan was previously arrested on a national security charge last year, one of more than 100 dissidents investigated under the new powers since they came into force in June.

At the time, the police's national security department said they suspected Wan had illegally processed funds to support people or organisations that advocate secessionist activities -- a potential reference to donations for Hong Kongers in Taiwan.

He has yet to be charged with a national security offence.