By Chris Hogg
BBC News, Hong Kong
Hong Kong's government has asked Beijing to settle a dispute over how long its next leader should serve.
Mr Tsang looks certain to be elected chief executive in July
It is only the second time that the authorities in Beijing have been asked to resolve an argument over the Basic Law, Hong Kong's mini constitution.
Pro-democracy activists condemned the move, arguing that it undermined Hong Kong's autonomy to run its own affairs.
Hong Kong's last leader, Tung Chee-hwa, stepped down last month, two years early.
Hong Kong's mini constitution, the Basic Law, says a chief executive should be appointed for five years.
But after consultation with legal scholars in Beijing, the Hong Kong government decided his replacement should serve out just the last two years of his term.
The suspicion is that this decision was reached for reasons of political expediency - that Beijing does not yet have enough confidence in the man widely expected to get the job, the acting chief executive, Donald Tsang.
Two legal challenges have been launched in Hong Kong's courts to try to get it overturned.
That has prompted Hong Kong's government to ask Beijing to step in and sort out the dispute.
Mr Tsang told lawmakers he was asking the mainland's most senior legislative panel, the National People's Congress Standing Committee, to settle the matter.
But pro-democracy lawmakers complained he was trying to pre-empt judicial proceedings. They accused him of gross disrespect for the rule of law.