The Civic Party has demanded that any meetings between it and Beijing officials be held at a neutral venue and be open for journalists to cover.
It also said it would not accept individual invitations to any of its six lawmakers.
One of the six, Dr Kwok Ka-ki, set out the demands yesterday as he confirmed he had been invited to attend a meeting on political reform at the central government's Hong Kong liaison office.
Kwok said it was unlikely he would accept the invitation, made over the phone by an office representative.
"We don't accept individual meetings, and … if we have to meet … we don't want it to be a closed-door discussion - they must meet the six of us at the same time, in places other than the liaison office," he said.
The Labour Party and Democratic Party said they had not received any such invitations.
The government's No 2 official lamented later that there was still "a long way to go" to reach consensus on the 2017 chief executive election despite the government's five-month consultation ending on Saturday.
"My colleague joked that in the next stage - when we table our own proposal to seek Legco's support - maybe we will have to change our 'Let's talk' slogan," Chief Secretary Carrie Lam Cheng Yuet-ngor said.
"And [we could] borrow the one from our commercial targeted against shops which block pavements: 'Hey, can you clear the way?'"
Views expressed yesterday illustrated the division.
The Beijing-loyalist Federation of Trade Unions proposed requiring candidates to win at least half of the nominating committee's support before they could run in a public election.
But the pro-democracy Civil Human Rights Front endorsed the proposal tabled by student-led Scholarism and the Federation of Students for the public to be able to nominate candidates.
Meanwhile, a group representing eight financial organisations and financial services lawmaker Christopher Cheung Wah-fung published a joint statement opposing the Occupy Central movement.
The full-page advert in three newspapers comes after 70 banking and financial sector workers wrote to President Xi Jinping last week demanding democracy, some saying they might join Occupy Central if their request was denied.