The departure of more members from a social worker regulator would not affect its operation, according to Secretary for Labour and Welfare Chris Sun, after six of them had left amid a looming reform of the statutory body.

According to the Social Workers Registration Board's website, Toby Ho and Grace Wong's terms ended on Thursday. Four others - Chan Kwok-bong, Adino Chung, Phyllis Luk and Lam Chiu-wan - also left earlier this month, leaving only two elected members behind.

"I noticed that several elected members chose to resign. This was their own decision," the labour chief told reporters on Friday.

"The new amendment bill is very clear. Even if members resign, it will not affect the board's operation."

The development came as lawmakers are set to start a second reading of a government bill aimed at revamping the regulator. It proposes increasing the number of appointed members from six to 17, while elected members will remain unchanged at eight.

The new body can also promptly disqualify social workers convicted of serious offences.

"If the Legislative Council passes the amendment bill on July 3, we plan to gazette it on July 5 and the old registration board will then cease to operate," Sun said.

"The sector, society, and the government all hope that it can be a seamless transition. To do that, we need to appoint members to the board as soon as the bill is gazetted."

The minister also defended the administration's decision to inform board members in advance that they have to take an oath of allegiance to the SAR on July 5, describing it as a "responsible" move.