The Secretary for Labour and Welfare, Chris Sun, on Sunday said employers must reach agreement with workers on rosters that don't give staff at least one day off each week.

The minister made the comment after being asked about the death of a Star Ferry captain who collapsed at work this week.

The ferryman's widow told the media that he was on his 23rd consecutive day on duty, under a system that requires staff to work 25 days before taking a five-day break.

Speaking to reporters before heading to Beijing, Sun said the Employment Ordinance requires workers be given one day off every week, but it also allows flexibility if bosses and workers agree on a different arrangement.

"You have to understand that, for some industries, their rosters may be unusual. So employers and workers are allowed to negotiate," he said. "But the key principle is that employers must get consent from their workers to adopt a flexible roster."

He said officials were in contact with Star Ferry chiefs to remind them of the requirements under the law.

The Star Ferry Company has said most of its workers want to keep the current rostering arrangement.

The labour minister's four-day trip to Beijing will include visits to the Hong Kong and Macau Affairs Office and the Ministry of Human Resources and Social Security.

Sun said he will also go live on line on China's largest recruitment platform to promote Hong Kong's talent search.