China's outgoing President Hu Jintao warned that corruption could prove fatal to the Communist Party's grip on power, as he addressed the opening of a pivotal congress that will usher in a new generation of Chinese leaders.

Speaking to more than 2,000 delegates inside Beijing's Great Hall of the People, President Hu said the party “must make sure that all are equal before the law.” He warned that failure to stem corruption could cause the collapse of the party and the fall of the state.

He did not mention ousted senior politician Bo Xilai, who has been accused of taking massive bribes and covering up his wife's involvement in the murder of a British businessman. The case has exposed high-level corruption and revealed deep rifts within the party.

During the week-long 18th Party Congress, Mr. Hu is expected step down as party chief and hand the position to Vice President Xi Jinping, who will take over as president in March.

Security was tight in central Beijing as the congress began. Next door to the congress venue, police moved in quickly early Thursday to stop a screaming protester in the heavily guarded Tiananmen Square. Hundreds of activists have already been placed under house arrest or kept out of the capital.

The city's taxi drivers have been told to disable their rear windows in a bid to stop passengers from distributing political material, while firefighters resolutely stood guard in Tiananmen Square, an apparent effort to stop any would-be self-immolators.

Even as authorities cracked down on dissent, President Hu made promises of political reform. He said the party must continue efforts to “carry out the reform of the political structure and make the people's democracy more extensive, fuller in scope, and sounder in practice.”

But he called on the people and their leaders to “march on the path of socialism with Chinese characteristics,” vowing that China would never copy a Western political system.

President Hu's 90-minute speech also stressed the need for a new model of economic growth in China, which has experienced slowing after decades of rapid expansion.

But he spoke most urgently on the need to battle corruption, telling delegates that they should “exercise strict self-discipline and strengthen supervision over their families and staff.” He said all those who break state and party laws, regardless of their position, “must be brought to justice without mercy.”