BEIJING — Hu Jia, a soft-spoken, bespectacled advocate for democracy and human rights in China, was awarded the Sakharov Prize for Freedom of Thought, Europe’s most prestigious human rights prize, on Thursday. The award was a pointed rebuke of China’s ruling Communist Party that came as European leaders were arriving in Beijing for a weekend summit meeting.

Mr. Hu, 35, was given the prize by the European Parliament despite warnings from Beijing that his selection would harm relations with the European Union.

Last year, Mr. Hu testified via video link before a hearing of the European Parliament about China’s human rights situation. Weeks later, he was jailed and later sentenced to three and a half years in prison for subversion based on his writings criticizing Communist Party rule.

Mr. Hu has been one of China’s leading figures on a range of human rights issues, while also speaking out on behalf of AIDS patients and for environmental protection. He had been considered a front-runner for the Nobel Peace Prize, but lost to the former president of Finland, Martti Ahtisaari.

“Hu Jia is one of the real defenders of human rights in the People’s Republic of China,” said the president of the European Parliament, Hans-Gert Pöttering. “The European Parliament is sending out a signal of clear support to all those who support human rights in China.”

The timing may make for a frosty weekend in Beijing, where European leaders are to meet with top Chinese officials at the Asia-Europe summit meeting, held every two years. This year, the global financial crisis is expected to dominate, and cooperation will be high on the agenda.

In Beijing on Thursday, José Manuel Barroso, the European Commission president, called for “unprecedented levels of global coordination.”

“It’s very simple: we swim together, or we sink together,” he said in comments reported by The Associated Press.

Behind the scenes, China had lobbied against Mr. Hu’s candidacy for the Sakharov Prize. On Oct. 16, Song Zhe, the Chinese ambassador to the European Union, wrote a critical letter to Mr. Pöttering.

“If the European Parliament should award this prize to Hu Jia, that would inevitably hurt the Chinese people once again and bring serious damage to China-E.U. relations,” Mr. Song wrote, according to The Associated Press.

China had also warned against awarding Mr. Hu the Nobel Peace Prize, and a Foreign Ministry spokesman, Qin Gang, had described him in scathing terms as a convicted criminal.

“The Chinese government will be upset,” said Teng Biao, a legal expert who has written essays with Mr. Hu. “But as a responsible nation that is trying to integrate into the international community, China has to understand that its conduct should follow international protocols. It should embrace the criticism as an opportunity to improve China’s human rights condition.”

Mr. Hu remains imprisoned in Beijing and could not be reached for comment. His wife, Zeng Jinyan, a prominent blogger and human rights activist, also could not be contacted. She has lived for months under house arrest with the couple’s infant daughter.

The award to Mr. Hu is an embarrassment for the Communist Party two months after China’s successful staging of the Olympic Games. During the Olympics, the Chinese government proved it could smoothly manage the world’s biggest sporting event, but the government also prevented demonstrations at designated protest zones, instituted broad censorship restrictions on the domestic news media and placed numerous dissidents under house arrest or surveillance.

Mr. Hu’s conviction in April was part of a nationwide crackdown against dissidents in what many human rights advocates considered a pre-Olympic silencing campaign. Mr. Hu, a Buddhist, has dedicated himself to a range of issues during the past 12 years, including environmental protection, helping AIDS patients, championing the legal rights of Chinese citizens and promoting greater democracy.

He also used a personal Web site and e-mail messages to become a one-man clearinghouse of information on rights abuses and other controversies that officials preferred to keep quiet.

“Whatever he does, he always stands in the forefront,” Mr. Teng said in an earlier interview. “Everything he wrote, everything he said, is straight from his heart. We have poor people and marginalized people in society whose voices are being muzzled. Hu Jia was trying to be the spokesman for the unheard voices.”

Mr. Hu graduated from Beijing’s Capital University of Economics and Business in 1996 and almost immediately plunged into China’s nascent civil society. He traveled to Inner Mongolia to plant trees as a measure to slow the advance of the Gobi Desert.

By 2000, China was facing the rapid spread of AIDS, a problem the government had initially denied and remained reluctant to publicly confront. Mr. Hu formed a nongovernmental organization, Loving Source, and focused on caring for people infected with H.I.V. in a blood-selling scandal in Henan Province.

Gao Yaojie, a prominent advocate for AIDS patients in China, recalled how Mr. Hu once rode a bicycle down a rutted dirt road to reach an isolated village decimated by AIDS. The road became narrower and potted with holes until Mr. Hu simply put the bike on his shoulder and walked to deliver help to a village where local officials were trying to cover up the problem.

“We didn’t do anything wrong,” Dr. Gao said in an interview earlier this month. “The only thing we did was to help H.I.V.-positive people. But we were always under great pressure from the government.”

Mr. Hu later began joining Internet petition campaigns calling for the release of political prisoners, while also calling on the authorities to uphold legal rights under the Chinese Constitution.

His activism quickly made him a target. In 2006, he spent 168 days under house arrest. Rather than disappear from public view, he produced a documentary, “Prisoners in Freedom City,” which included video of state security agents harassing his wife as she tried to leave their apartment complex, which is known as Bo Bo Freedom City.

Indeed, as Mr. Hu faced constant surveillance and harassment, he continued to use the Internet to push for political reform and publicize abuses. His testimony via video link before the European parliamentary committee came last November.

“It is ironic that one of the people in charge of organizing the Olympic Games is the head of the Bureau of Public Security, which is responsible for so many human rights violations,” he testified. “It is very serious that the official promises are not being kept before the Games.”