Secretary for Food and Health Ko Wing- man is under pressure to talk with doctors' groups on the controversial Medical Council reform bill, after its second reading was aborted due to a lack of quorum.

More than 450 protesters from various medical associations threatened to stage another sit-in when the Legislative Council meeting resumes on Wednesday if the government refuses to listen to them.

Groups including the Medical Association, Doctors' Union, Public Doctors' Association, Frontline Doctors' Union, Medecins Inspires and medical student associations from the University of Hong Kong and Chinese University arrived outside the Legco complex for the sit-in at 2pm, an hour before the second reading of the Medical Registration (Amendment) Bill 2016 was scheduled to start.

With a one-week break before the meeting resumes, the government has no excuse not to meet the sector, said Civic Party legislator and doctor Kwok Ka-ki.

Doctors are angry Ko has never consulted their opinions since the bill was tabled in February. Its passage instead is being rushed, they added.

The bill seeks to change the composition of the regulatory body for doctors to ''enhance transparency and efficiency for investigating complaints.''

Most doctors call it a "scam" that will compromise professional autonomy and patients' welfare.

"We may lose this battle but we have to make it known that the medical sector is against the amendment," said Gabriel Choi Kin, Medical Association council member and incoming president.

The pro-establishment camp has voiced their support for the bill.

The Democratic Party said its lawmakers will support the government's bill if Kwok's amendment to make the four existing appointed doctor positions elected seats is passed. However, Kwok's party already said it will vote against the bill.

The Legco meeting was called off due to a lack of quorum at 6.30pm, one lawmaker short of the required 35. The bell rang 15 times yesterday.

Kwok made eight calls for a head count, while medical sector lawmaker Leung Ka-lau made seven, including the one that adjourned the meeting.

Leung earlier tabled 110,000 amendments on the bill but were all thrown out by Legco president Jasper Tsang Yok-sing.

Ko said: "I was very worried that the bill would not be approved, since there are only two meetings left before the legislative session ends." He sidestepped the question about whether he will meet the sector.

The filibustering lawmakers were welcomed by cheers and applause from the protesting crowd.

"Adjournment isn't necessarily a bad thing, as it allows more time for discussion," Leung said, adding he will use the seven days to talk to his pro- establishment colleagues on the medical sectors' concerns.

The bill will add four more chief executive-appointed lay members to the 28-strong council.

Ko has said three out of the additional four appointed lay members will be first chosen among patients rights groups but his attempt to allay concerns failed.