Chinese police arrested a human rights campaigner in the country's southwest for "possession of state secrets" after he offered help to parents of children killed in the region's massive earthquake, his family said.

Huang Qi was detained in quake-hit Sichuan province on June 10, and on Friday police told his mother of his formal arrest on the secrets charge, his wife Zeng Li said by phone on Saturday.

Police in the Wuhou area of Sichuan's provincial capital Chengdu, where Huang was arrested, said they had no knowledge of the case.

But his arrest appeared related to his support for parents whose children died in the May 12 quake, when many schools crumbled, raising accusations of shoddy building and lax safety checks, said his wife and rights groups.

"The police didn't say why, but we think it was because of when he went to help in the quake area with food and money and met many parents who'd lost children," she said.

Huang's contacts with foreign journalists may also have brought official wrath, Zeng said.

China is readying to hold the Beijing Olympic Games, and Communist Party authorities have demanded sweeping steps to stifle protests and dissent ahead of the event.

Sichuan authorities have sought to silence protests and collective grieving by the parents, whose complaints initially drew widespread domestic media attention.

The quake killed about 70,000 people, with thousands still counted as missing and mostly likely dead. The Olympic torch will pass through quake-hit areas days before the Games open on Aug 8.

Huang has not been allowed to see his lawyer or family, said Zeng. Human rights groups have said vague state secrets and subversion charges are often used to silence dissidents.

"Huang has been arrested solely for peaceful expression of opinion," said the Chinese Human Rights Defenders group in an emailed statement.

Huang, 45, has run his own Tianwang Human Rights Center and a Web site (http://www.64tianwang.com) critical of the Communist Party's restrictions on political rights.

He was convicted in 2003 of "inciting subversion of state power" and released from jail in 2005.