Chinese investigators have concluded that an activist who said he was paralyzed after assailants broke his neck inflicted the injury on himself, his son said Thursday.

"We cannot accept this decision," said Fu Bing, whose father, Fu Xiancai, criticized the government's treatment of people who were forced to relocate as a result of the Three Gorges dam project.

Fu Xiancai was injured three weeks after German public television broadcast an interview in which he said he had been threatened and beaten for complaining about inadequate compensation for relocated residents.

CountryWatch:China

He says that on June 8, he was called into the Zigui County Public Security Bureau in Hubei province and criticized for his television appearance. He was attacked after leaving the police station, he said.

On Wednesday, the head of the security bureau's forensics department and another county official told Fu Bing that experts concluded the injuries were self-inflicted, Fu Bing said.

Investigators refused to release other details, but said they found no other footprints at the scene, indicating his father had been alone, Fu Bing said.

A man who answered the phone at the security bureau Thursday said he was "unclear" about the case and refused to give his name.

Authorities told the Fu family not to appeal the decision or file a new complaint, Fu Bing said.

"My father was beaten with a wooden stick, first on his thighs, then repeatedly on his neck. He was beaten until he fell to the ground and lost consciousness. His body went numb," Fu said.

"He is very upset about the results of this investigation," he said. "He will definitely appeal."

Fu Xiancai underwent an operation last month that may enable him to use a wheelchair, but doctors have said he will not walk again.

The New York-based group Human Rights in China said it was "strongly concerned" about the Chinese investigation.

The rights group said authorities were "unlawfully pressuring Fu Xiancai to forgo any legitimate appeals process and refusing to disclose the experts who determined that Fu could have single-handedly struck himself from behind with such force as to shatter three of his vertebrae."

Political activists in China regularly face suppression by police and security forces. In recent years, activists have complained increasingly about attacks by thugs who they claim act on orders from authorities.

The Three Gorges dam was designed to stop flooding on the Yangtze River and produce enough electricity to light Shanghai. But it required relocating 1.13 million people, generating anger and resentment. The issue is particularly volatile around Zigui, home to many relocated people.

Germany's government has demanded an investigation and punishment for those responsible. The German Embassy in Beijing gave Fu $7,510 to help pay for the surgery.

Fu Bing said his 47-year-old father is slowly recovering, but his muscles are weak and he cannot sit up.

"He's been beaten before, although never this seriously," he said. "But his will is still very strong."