One of Hong Kong’s most strident pro-democracy figures has been arrested and the newspaper he runs searched by police in a stark escalation by authorities enforcing new national security laws brought in by Beijing.

The raid on Apple Daily, Hong Kong’s largest pro-democracy daily paper, and arrest of Jimmy Lai and senior executives, were condemned by activists and journalists, who said they marked “the day press freedom officially died”.

Lai, a 71-year-old media tycoon and outspoken funder of the pro-democracy movement, was arrested alongside six others including his son, on suspicion of “collusion with foreign forces” and conspiracy to commit fraud on Monday morning.