Xu sued the State Environmental Protection Administration last month for naming Yixing, in the prosperous eastern province of Jiangsu, as a model city, she told Reuters.

"The pollution here is very serious and there are lots of complaints from residents," Xu said of the city known for its clay and teaware. "We do not think the city is qualified to be a model city for good environment," she said.

The Beijing First People's Intermediate Court, where she lodged the case, had so far refused to take up the case, she said, adding that she would continue trying to start legal proceedings until SEPA withdrew the award.

Her husband, Wu Lihong, a candidate in 2005 in a national campaign to name 10 people who "moved China" with their service to society, was arrested in April and will face trial on June 12 charged with extortion and blackmail.

"I feel very sad for my husband, and I have been forbidden to visit him since he was arrested," Xu said.

"Only our lawyer was granted a visit once, and Lihong told her that he was tortured and she saw bruises on his body," she said.

Detention and harassment of activists is common in China.

In 2006, a court in neighbouring Zhejiang sentenced an environmental activist to a year and a half in prison for "illegally obtaining state secrets".

Taihu Lake, with an area of 2,420 square km (934 square miles) and a shoreline of 400 km (250 miles), straddles the border of Jiangsu and Zhejiang provinces and is home to more than 60 kinds of fish.

Xinhua said tap water in eastern Wuxi was back to normal after the algae, fed by industrial and agricultural waste, caused a drinking water crisis.