HONG KONG -- Hong Kong national security police arrested five top editors and executives of the outspoken newspaper Apple Daily and its parent company, and raided the group's offices early Thursday morning in relation to allegations of "collusion with foreign forces."

Collusion with foreign forces is one of four offenses created under the national security law imposed on the city by Beijing a year ago.

In two news releases, the government said the offices of Apple owner Next Digital and the homes of the five people arrested were searched. This was part of "gathering evidence for a case of suspected contravention of the national security law," as police secured a warrant allowing for the seizure of journalistic materials.

Apple Daily's website reported that the raid started around 7:30 a.m. Over 100 officers from the police department and its national security bureau blocked all entrances to the media company's headquarters in the eastern Kowloon neighborhood of Tseung Kwan O, forcing all who entered to provide their personal details.

Those arrested include Next Digital Chief Executive Cheung Kim-hung and Chief Operating Officer Royston Chow, as well as Ryan Law, Apple's chief editor.

Jimmy Lai, the founding chairman of the paper, is serving a 20-month prison sentence after he was convicted in three cases for joining unauthorized assemblies in 2019. His controlling stake in Hong Kong-listed Next was frozen last month by the authorities, who cited security law collusion charges that he also faces.

During Thursday's raid, police stopped journalists from taking photographs or videos, Apple Daily reported. This follows a larger raid on Next's offices last August, which was broadcast live on TV news channels and video streams.

Ahead of the start of trading in Hong Kong, Next Digital announced that trading in its shares had been suspended.