Trump praises 'brave' media mogul

US President Donald Trump on Wednesday called arrested Next Digital media mogul Jimmy Lai Chee-ying a "brave man" and expressed his support for the pro-democracy advocate who was briefly detained last week.

"I sent him best wishes," Trump told reporters at the White House, AFP reports.

Lai was among 10 people detained on August 10 under a national security law imposed by Beijing, as around 200 police officers searched the newsroom of his Apple Daily head office in Tseung Kwan O Industrial Estate.

The 71-year-old was cheered by staff and handed a bouquet as he returned to the newsroom two days later following a late-night release on bail after 40 hours in custody.

During the White House briefing, Trump called Lai "certainly a brave man."