A CPPCC member has threatened to jump off the Two IFC tower if Chief Executive Leung Chun-ying passes a lie detector test over illegal structures.
Lew Mon-hung turned his back on the man he once supported as the city's leader in an interview with iSun Affairs magazine published last week.
He said Leung lied over his handling of illegal structures at his Peak home and considered the pan-democrats "enemies".
He also accused Leung of breaking a promise to appoint him to the Executive Council, or recommend him for membership of the Chinese People's Political Consultative Conference Standing Committee.
Challenging the chief executive to the polygraph test, Lew said yesterday: "What I told the magazine about Leung is absolutely true.
"If I cannot pass the polygraph test, I will jump to my death from Two IFC. If Leung fails, all he needs to do is to apologise to the people of Hong Kong."
At 420 metres high, the Two IFC building is the second-tallest in Hong Kong.
Lew is on bail after he was arrested on January 8 as part of an Independent Commission Against Corruption inquiry into his listed company Pearl Oriental Oil. His business partner was also arrested.
Sources said Lew was unlikely to retain his CPPCC seat, given the investigation. One said: "An ICAC probe takes a long time and the fact Lew was arrested makes it impossible for him to continue doing his duty [as a CPPCC member]."
Embattled Leung again denied Lew's claims yesterday, but refused to say whether he promised Lew an Exco seat.
He deflected questions about whether he could pass a lie-detector test and would not elaborate on his relationship with Lew.
He also said he "would not interfere with the work of law enforcement agencies, including the ICAC".
The League of Social Democrats and the NeoDemocrats yesterday filed complaints to the ICAC alleging Leung could have breached bribery laws by offering an Exco seat to Lew in exchange for his support.
And Secretary for Development Paul Chan Mo-po and Exco member Jeffrey Lam Kin-fung denied they struck deals with Leung for government positions.