Hong Kong's political system would "certainly" risk legal challenges if it embraced at this stage an international covenant demanding universal suffrage, the city's solicitor general said.
Frank Poon Ying-kwong was explaining to a UN human-rights hearing in Geneva last week why the city had still not implemented the International Covenant on Civil and Political Rights (ICCPR) provision on "equal and universal suffrage".
The Hong Kong government has opted to "reserve" - in effect to skirt - ratification of Article 25(b) of the covenant, which says all measures should be taken to implement the goal of equal and universal suffrage.
"It is premature to withdraw the reservation before this goal [implemented in a gradual and orderly manner consistent with the Basic Law] is achieved," Poon said, according to a partial transcript prepared by University of Hong Kong law professor Puja Kapai and accepted by the Department of Justice.
"If this [withdrawal] is done," Poon said, "there could be and certainly would be domestic challenges brought before the HKSAR courts to challenge the existing system. We cannot be diverted and distracted from the challenge to implement democracy by unnecessary lawsuits."
Beijing has promised that the chief executive can be selected by universal suffrage in 2017 and the Legislative Council in 2020. But the future of functional constituencies - which analysts say are not in line with the ICCPR provision - has not been decided.
Poon's account did not seem totally convincing to UN officials, according to Civic Party lawmaker Dr Kenneth Chan Ka-lok, who attended the meeting.
"Poon was questioned by members on why the reservation could not be withdrawn, given the government's ultimate goal of universal suffrage," Chan said. "To me, his explanation was to some extent incomprehensible."
Kapai said committee chairman Nigel Rodley "warned that it was undesirable for Hong Kong to maintain its reservation".
Meanwhile, the highest-ranking mainland official working for the UN yesterday expressed confidence in Hong Kong's political development, adding that a "mature" civil society would be the key to the road ahead.
Wu Hongbo, the UN Undersecretary General for Economic and Social Affairs and a diplomatic veteran of Sino-British pre-handover negotiations, also said that whatever system Hong Kong chose, it should be "consistent with local conditions".
"I believe Hongkongers and the SAR government have the wisdom and have the political commitment to bring forward their political structure within the terms of reference provided by the Basic Law," Wu said.
"Hongkongers, they have the wisdom to solve their problems and to find their political system," he said in remarks that followed a speech to the China Energy Fund Committee, a local think tank.
Describing his remarks as "personal observations", Wu noted the complex evolution of political systems, saying that a great deal of political progress had been made in Hong Kong in the 16 years since the handover compared to the 150 years of British rule.
He said even Western democracies tailored systems to local conditions and added that a "mature civil society" would be vital to ensuring the successful implementation of a democratic system - pointing out problems in countries that lacked one.