ROME — The number of prisoners put to death worldwide decreased in 2008, a human rights group said today, adding that China retained its position as the world’s top executioner.

Executions in the United States were down from last year, while Iran and Saudi Arabia appeared near the top of the list of the world’s top executioners, the anti-death penalty group Hands Off Cain said in a report about 2008 and the first six months of this year.

The group said that at least 5,727 executions were carried out in 2008, down from 5,851 the year before. It said that 46 countries retained the death penalty last year, three fewer than in 2007, with Burundi and Uzbekistan abolishing capital punishment, and Sierra Leone establishing itself as a de facto abolitionist by not having carried out any executions for more than 10 years.

The report said China accounted for at least 5,000 executions — or 87.3 percent of the total — the same estimate as last year.

Hands Off Cain said its estimates are based on reports by the media and other human rights groups since the exact number of executions in China remains a state secret.

Iran executed at least 346 people last year, down from 355 in 2007; Saudi Arabia put 102 people to death, while in 2007 it accounted for 166 executions. As of June 30, the number of executions in the two countries included four minors in Iran and three in Saudi Arabia, in violation of the U.N. Convention on the Rights of the Child, the report said.

The Rome-based group also said a large number of executions were based on terrorism charges in Afghanistan, Indonesia, Iran and Iraq. China also ties repression against Tibetans and Uighurs — a Muslim minority in the country’s restive far western region of Xinjiang — as part of the war on terrorism, it said.

The United States executed 37 people — five fewer than 2007, continuing a downward trend in the country since 1999, when the number of executions peaked at 98, according to Hands Off Cain. Nearly half the U.S. executions in 2008 were carried out in Texas.

The report also said 111 death sentences were handed down in the United States last year, the lowest number since the reintroduction of the death penalty in 1976.

The group assigned the “Abolitionist of the Year” award to New Mexico’s Gov. Bill Richardson and Gail Chasey, a member of the state’s House of Representatives, for their role in abolishing capital punishment in the U.S. state in March.