All pro-democracy legislators are set to shun an invitation to a spring reception hosted by the Liaison Office in Sai Wan next Tuesday.
Office director Wang Zhimin invited all legislators to a banquet in "return" for a luncheon by the Legislative Council in April last year.
"I welcome all friends in Central to gather in Sai Wan for our friendship," he said.
"Director Wang Zhimin, all deputy directors, the secretary general and all department heads will be there to share the joy of the lantern festival," the office said in the invitation. "Legislators who plan to attend should reply by Friday."
Wang said in January last year he "heard many people saying that it will be beneficial for Central and Sai Wan to walk closer."
But convener of the democracy camp meetings Claudia Mo Man-ching said it is a "sin" if pan-democrats enter the Liaison Office and it would "send the wrong message."
Both the Civic Party and the Democratic Party described the banquet as meaningless. Civic Party leader Alvin Yeung Ngok-kiu said "no concrete issues will be discussed there."
Democratic Party chairman Wu Chi-wai said nobody from his party will attend. "We, the Democratic Party, are dissatisfied with the ruling attitude of Beijing and the Liaison Office as it puts emphasis on the one country while belittling the two systems."
Both Fernando Cheung Chiu-hung of the Labour Party and Cheng Chung-tai of the Civic Passion said they and the Professionals Guild will not make an appearance.
Pierre Chan Pui-yin of the medical sector, who is considered more centrist, said he is busy every Tuesday working in public hospitals and will not leave his patients "just to attend these activities."
Chairwoman of the Democratic Alliance for the Betterment and Progress of Hong Kong Starry Lee Wai-king said the office has made the first step of communication and she hoped the pan-democrats will accept the invitation.
Lo Wai-kwok, head of the Business and Professionals Alliance, said pan-democrats should take the chance to voice their opinions to the office.
The leader of the Liberal Party, Felix Chung Kwok-pan, said it was "nuts for Mo to call going inside the Liaison Office's building a sin."