BEIJING — China faced international condemnation on a new front yesterday after jailing its most prominent human rights activist for three and a half years.

Hu Jia, 34, was sentenced for inciting subversion after a one-day trial in which he was accused of criticizing the ruling Communist Party.

Human rights groups say the party was determined to deal with Mr. Hu in advance of the Beijing Olympics because of his ability to bring international attention to a range of sensitive causes. The court said that Mr. Hu had received a lenient sentence because he had “confessed,” but the European Union and America both immediately condemned the trial.

“In this Olympic year, we urge China to seize the opportunity to put its best face forward and take steps to improve its record on human rights and religious freedom,” a statement from the American Embassy in Beijing said.

Mr. Hu first became active politically on environmental issues, a relatively safe area.