A HKMAO spokesman said the central government had hoped the Hong Kong government would conduct thorough consultation with Beijing before reviewing its political system. Subsequently, the Hong Kong government appointed a taskforce to consult with the NPC officials and the HKMAO on 'principles and legislative process' relating to changes.

The central government has not yet spelt out which principles on the development of Hong Kong's political system it is concerned about. But local legal experts and politicians believe it involves interpretation of ambiguous phrases in Article 45 and 68, as well as Annex I and II of the Basic Law.

Annex I says: 'if there is a need' to amend the method for selecting the chief executive in 2007, the changes must be approved by two-thirds of the Legislative Council, the chief executive and the NPC Standing Committee.

Under Annex II, 'if there is a need' to change the Legco elections system the first two hurdles must be passed, but reporting to the committee is only required 'for the record'.

Under Articles 45 and 68, the methods for electing the chief executive and Legco members shall be specified in the light of the 'actual situation' in Hong Kong, and in accordance with the principle of 'gradual and orderly progress'. The clauses state electing Hong Kong's leader and all Legco members by universal suffrage are the 'ultimate goal'.

It remains unclear who - the central government or Hong Kong - decides whether there is a need to change the electoral system, and what is meant by 'gradual and orderly progress' in the light of the 'actual situation'.

During his six-day trip to Hong Kong which ended last Tuesday, former Basic Law drafter Xiao Weiyun said the central government had the power to decide on the development of Hong Kong's political system because it had a bearing on the relationship between the central government and the special administrative region, as well as on the city's long-term prosperity.

Fellow mainland legal expert Xia Yong, who visited Hong Kong along with Professor Xiao, added that the central government had a decisive say over Hong Kong's political development and was empowered to oversee the process.

Shiu Sin-por, executive director of the One Country, Two Systems Research Institute, said the mainland legal experts had grounds for saying that the central government had the power to decide because the Basic Law was a national law.

But the Article 45 Concern Group, members of which include the former heads of the Bar Association, Ronny Tong Ka-wah and Audrey Eu Yuet-mee, said that the reform process had to be initiated in Hong Kong.

Mr Shiu said it was difficult to initiate changes to electoral methods in Hong Kong if the central and Hong Kong governments and Legco held different views on whether there was a need for change.

The phrases 'gradual and orderly progress' and 'actual situation' are more controversial. Professor Xiao stuck a controversial footnote to the phrase 'gradual and orderly progress' earlier this week, when he said the Basic Law drafters' consensus was that the ultimate goal of a general election would be achieved in the final stages of the 50-year lifespan of 'one country, two systems', possibly in the 2030s or 2040s. 'We [the drafters] never considered election of the chief executive by universal suffrage in 2007,' he said.

Mr Tong said the words 'actual situation' in Hong Kong, rather than 'gradual progress', should be the guiding principle for reforming Hong Kong's political system. 'The actual situation is very clear: various opinion polls show that about 70 per cent of people in Hong Kong want the chief executive to be elected by universal suffrage in 2007,' he said.

For mainland legal experts the 'actual situation' in Hong Kong is obvious. Xu Chongde, another mainland drafter of the Basic Law, said now was not the right time to launch a constitutional review, adding that people should concentrate on reviving the economy.

'The existing political structure of Hong Kong has functioned quite efficiently in the past six years and the problems facing Hong Kong since the handover do not lie in flaws in the city's political system,' he said.

Tam Yiu-chung, a Hong Kong member of the Basic Law Drafting Committee, said the drafting committee did not go into detail on the meaning of 'gradual progress' or who was empowered to decide whether there was a need to change the system. 'The drafters preferred setting a timetable for political development in Hong Kong in the first 10 years after the handover and left the future constitutional framework open for discussion in the future,' he said.

Priscilla Leung Mei-fun, associate professor at City University of Hong Kong's school of law, said ambiguities in the Basic Law concerning changing Hong Kong's electoral system reflected the failure of drafters to reach consensus.

DAB chairman Ma Lik proposed the Hong Kong government consider asking the NPC Standing Committee to clarify the grey areas in Annexes I and II and the exact meaning of 'gradual progress' and 'actual situation' in the review of the city's future constitutional framework.

Professor Leung said the scenario of another interpretation by the NPC Standing Committee might happen if the Hong Kong community and the central government failed to iron out their differences on the relevant provisions.

But the debate on the development of Hong Kong's political system may be more a political issue than a legal one.

A Hong Kong deputy to the NPC, who spoke on the condition of anonymity, said Beijing had reservations about introducing universal suffrage in Hong Kong in 2007 and 2008. 'The central government is obviously worried that pro-democracy politicians would seize power in Hong Kong if general elections are held here.'

Mr Shiu said he opposed any expansion of electoral politics in Hong Kong in 2007 because it would undermine governance in the city. 'It's time for a respite for the Hong Kong community,' he said. 'Hong Kong people are quite rational. They would not follow the democrats to confront the central government.'