A leading Chinese human rights lawyer says he was released from detention Sunday, but still might face prosecution on charges of tax evasion.

Xu Zhiyong, co-founder of a legal-aid group known as the Open Constitution Initiative or Gongmeng, had been out of contact since security officials seized him from his home on July 29.  He was formally arrested last Tuesday on charges of tax evasion.

Xu said Sunday he was released on bail pending trial.

Chinese authorities shut down the legal rights center more than a month ago for alleged nonpayment of taxes.  Members of the group reported nearly two weeks later that Xu had been detained by police, and that they could not contact him.

The group has helped victims of China's tainted-milk scandal and offered assistance in human-rights cases.  It also has issued a report criticizing the Chinese government's policies toward Tibet. 

Rights groups say the latest developments are part of a widening crackdown on lawyers, rights activists and non-governmental organizations ahead of the 60th anniversary of the Chinese communist state.

Preparations are under way for a huge official celebration of the anniversary on October 1.  Rights activists expect the government will try to prevent any public demonstration of dissent during the festivities.

China recently revoked the licenses of 53 Beijing lawyers, most of them prominent human-rights advocates.  Amnesty International has condemned the crackdown on lawyers as a major blow to the human-rights defense movement in China.

In a widely quoted statement earlier this year, Xu said his Gongmeng group aims to help build the rule of law and advance Chinese society by objectively and independently studying human-rights protections, the situation in Tibet and other issues.

One of the government's main charges against Xu's group alleges that no taxes were paid on a $100,000 grant the Open Constitution Initiative received from Yale University.  Xu has been a visiting scholar at Yale Law School on several occasions. 

Some information for this report was provided by AFP and Reuters.