CHINA’S COMMUNIST leaders ought to regard activists like Xu Zhiyong as allies in their effort to reform the country’s economy, root out corruption and create a more representative and sustainable political system. Instead, the 40-year-old lawyer was put on trial Wednesday in Beijing, and at least six of his followers were due in court on Thursday and Friday. Far from regarding Mr. Xu’s New Citizens’ Movement as constructive, the regime of Xi Jinping is “terrified” of it, as Mr. Xu told a court from which journalists and Western diplomats had been barred.

What could be so scary about a group that peacefully advocates for the public disclosure of officials’ assets? A report released just before Mr. Xu’s trial by the Washington-based International Consortium of Investigative Journalists offered an indication. In poring through a cache of 2.5 million leaked files, the center discovered nearly 22,000 offshore bank accounts held by citizens of China and Hong Kong — including some linked to the family of Mr. Xi and four other present or former members of the Politburo Standing Commitee. While the offshore accounts, in havens such as the British Virgin Islands, aren’t necessarily illegal, they show that the country’s top rulers have tried to hide, rather than reveal, their families’ assets — which in some cases amount to billions of dollars.

In his first year in power, Mr. Xi has tried to curry public favor by launching an anti-corruption campaign that he claims will tackle “tigers” as well as “flies.” But the raw persecution of Mr. Xu’s movement shows that the new leader mainly intends to protect what has become a massive network of official corruption. Fear that high-level graft will be exposed is helping to drive a political crackdown that has swept up more than 150 activists, intellectuals and journalists, tightened control over the Internet and silenced Chinese media — which haven’t been allowed to report on the trials of Mr. Xu and his fellow activists. Pressure has been raised on Western correspondents in China, especially those who attempted to report on the vast wealth accumulated by the families of senior figures such as former prime minister Wen Jiabao.

The repression is contemptible on human rights grounds, but it also ought to be worrying to all — starting with the Obama administration — who hope Mr. Xi will succeed in addressing China’s accumulating economic, environmental and social ills. That can’t happen without a freer civil society and media that can document abuses and support reforms. Mr. Xu’s New Citizens’ Movement aimed to work within the Chinese constitution; it hoped to be accepted by the new leadership. By crushing the movement, Mr. Xu said in his court statement, the regime is attempting to “block China’s road to democratic constitutional government through peaceful reform.” It also is ensuring that its effort to restructure China’s economy and strengthen the Communist Party’s rule will fail.