BEIJING (AP) — Authorities are tightening restrictions on the extended family of a blind activist whose flight from house arrest in rural China into the protection of the U.S. Embassy in Beijing set off a diplomatic dispute.

Activist Chen Guangcheng and the Chinese Human Rights Defenders say authorities in Chen’s hometown in eastern China have placed Chen’s elder brother and sister-in-law under house arrest.

Chen said Thursday his mother told him by phone that police are searching for the wife of Chen’s nephew, Chen Kegui, and have threatened to detain Chen’s sister-in-law if the wife does not show up.

Activists who have been in contact with Chen’s extended family say around a dozen of his relatives are under some kind of house arrest.