They said the recent jailing of a top dissident underlined similar worries.
China submitted its first draft law covering martial law to the National People's Congress, or parliament, for approval Wednesday, the official Xinhua news agency said.
Last week, China drew international condemnation by imprisoning its best-known dissident, Wei Jingsheng, for 14 years for conspiring to subvert the government.
Wei, 45, a 1995 Nobel Peace Prize nominee, regarded as the father of China's modern democracy movement, was convicted of financing the democracy movement.
Analysts said the moves signal the leadership's nervousness about security in the post-Deng era.
"They're all part of the government's efforts to maintain stability after Deng," said an editor of a government publication who spoke on condition of anonymity.
Deng, 91, no longer holds any office and has not appeared in public for almost two years, but remains influential.
His health is a matter of intense speculation in China and neighboring countries because his death is expected to trigger a scramble for power among those eager to succeed him as the de facto leader of the world's most populous nation.
A Chinese academic with ties to the Communist Party said the leadership was politically insecure and obsessed with stability. He likened the situation to China being "surrounded by dried wood and [the government] snatching away and locking up all lighters and matches, scared that a spark might trigger a fire that cannot be controlled."
During certain periods of Communist rule since 1949, the government has imposed martial law or military rule in certain areas, most recently in Beijing in June 1989 when it sent in the military to put down student-led, pro-democracy demonstrations.
The draft submitted to parliament is designed to give the state legal teeth to impose martial law, diplomats said.
"They are covering their backs in view of 1989 ... to establish a proper legal basis," a Western diplomat said.
The 1989 imposition of martial law, to crush the Tiananmen Square pro-democracy demonstrations, was apparently based on clauses in the constitution that call for the state to "maintain public order, suppress treasonable and other counter-revolutionary activities." They do not specifically mention martial law.
In the future, "martial law will be declared in a state of emergency in which unrest, rebellion or riot, which endanger the country's unity, security and social order, occur and no other effective measure can maintain social order," Xinhua quoted one of the drafters as telling parliament. Xinhua did not say when the bill would be passed.
President Jiang Zemin stressed the importance of political and social stability in a speech splashed across the front page of the People's Daily on Thursday.
"Political and legal departments must take it as their sacred duty to attack sabotage by hostile elements, strike serious criminal and economic offenders and crack down on prostitution, pornography, drug production and trafficking and criminal gangs," he said.
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