Authorities in China have started arresting people connected with activist Chen Guangcheng, who was under strict house arrest when he escaped last week.
Fellow activist Hu Jia has been detained, Hu's wife said Sunday on Twitter. There are also reports Chen's brother and nephew are among those who have been detained by police on suspicion that they helped the blind lawyer flee his heavily guarded house in Dongshigu village.
On Saturday, activists said Chen was under U.S. protection and suggested the only place he could be was inside the U.S. Embassy in Beijing, 600 kilometres from his home.
In another development, U.S. Assistant Secretary of State Kurt Campbell arrived in China on Sunday, but declined to discuss his agenda with reporters. His trip had originally been scheduled to begin later in the week to coincide with two days of high-level U.S.-China talks that begin Thursday.
There is speculation the U.S. delegation will be hearing China's concerns over both the Chen case and a possible U.S. military deal with Taiwan. The administration of President Barack Obama has raised the possibility that it could sell new jet fighter aircraft to Taiwan to help redress the island's air power deficit with China.
Neither China nor the United States has commented on whether Chen, 40, has sought refuge in the U.S. Embassy, as activists contend, highlighting the sensivity of the issue.
On Friday, Chen released a video message appealing to China's premier to protect his family from reprisals. The whereabouts of his wife and young son remain unknown.
Chen came to prominence after revealing abuses under China's one-child policy.
He was jailed for four years and then placed under house arrest for 20 months after accusing local officials of forcing thousands of women to have abortions.