The Hong Kong government unveiled a package of limited political reforms on Wednesday that would add seats to the legislature and expand the committee China uses to appoint the territory's chief executive. But opposition democrats immediately condemned the plan as inadequate and vowed to block it.

The quick and forceful rejection of the proposal set the stage for another public showdown over China's refusal to allow residents in this former British colony to directly elect their political leaders.

Pro-democracy lawmakers announced plans for a protest march in early December and said they would vote as a bloc against the proposal. Constitutional changes in Hong Kong require the support of two-thirds of the legislature, or 40 of its 60 members, and the democrats hold 25 seats. As a result, if the opposition stays united, it could prevail, raising the possibility that Hong Kong's political system will remain unchanged when the territory's next chief executive is selected in 2007 and the next legislature is elected in 2008.

The strategy represents a gamble by the democrats that the public will blame the government for failing to put forward more extensive reforms rather than the opposition for rejecting a plan that would allow at least a measure of greater representation in Hong Kong.

Donald Tsang, the chief executive named by Beijing this year, portrayed the proposal as the best he could get for Hong Kong given the constraints imposed by the Chinese government. "The government has left no stone unturned in formulating a package that embodies democracy and openness to the highest extent possible," he said, adding that the policy was consistent with a decision by the Beijing government last year that ruled out direct elections in Hong Kong in 2007 and 2008.

Tsang said opinion polls commissioned by the government showed that 60 percent of the public supported his proposal. He also won support from some members of the pro-democracy camp who do not hold seats in the legislature.

Opposition leaders said Tsang's plan would introduce so little change that endorsing it would be a betrayal of the public. Several noted that it did not include a timetable for achieving universal suffrage, which the democrats had demanded. Others accused Tsang of designing a plan rigged to guarantee that China's Communist Party can continue to control the Hong Kong government.

The proposal calls for doubling the size of the 800-member election committee that chooses the chief executive and is currently stacked with prominent citizens loyal to Beijing. Most of the increase would be achieved by giving seats to 529 district councilors, residents who sit on neighborhood committees and serve as advisers on issues such as traffic and street cleaning.

About four-fifths of the councilors are elected, but 102 are appointed by the chief executive. Several democrats had urged Tsang not to give the appointed councilors seats on the election committee.

"The government appoints some people, and then allows these people to sit on a committee to elect the chief executive. It is in effect vote-planting," said Yeung Sam, a veteran legislator and the former chairman of the Democratic Party.

Tsang's plan also calls for expanding the legislature, with five new seats to be filled in general elections and five others to be elected by the district councilors. The public now elects 30 members of the legislature, with the remaining 30 chosen by small constituencies of professionals, most of whom are loyal to Beijing.

Pan reported from Beijing.