At least 24 people a week were executed officially last year and a further 64 sentenced to death, Amnesty International said in a report on Tuesday, adding that this was likely to be an underestimate.
In Olympic host China, where executions are a state secret, the human rights group said it had established that at least 470 people were executed - equivalent to nine a week - and a further 1,860, or 35 a week, were sentenced to death.
The figures make China the world's most prolific state executioner, Amnesty said.
"The secretive use of the death penalty must stop: the veil of secrecy surrounding the death penalty must be lifted," it said.
"Many governments claim that executions take place with public support. People therefore have a right to know what is being done in their name."
In total at least 1,252 people were executed in 24 countries last year and 3,347 sentenced to death in 51 countries, AI said, adding that some 27,500 people were now on death row globally.
Second to China was Iran with 317 executions, followed by Saudi Arabia on 143, Pakistan on 135 and the United States on 42. Between them, these five countries accounted for 88 percent of all known executions.
Amnesty International said the totals had risen from 2006 in Iran, Saudi Arabia and Pakistan.
It noted that in December 2007 the United Nations General Assembly voted by a large majority for a resolution calling for an end to the death penalty.
"The taking of life by the state is one of the most drastic acts a government can undertake. We are urging all governments to follow the commitments made at the U.N. and abolish the death penalty once and for all," Amnesty said.
