Amnesty's data showed the number of executions worldwide fell to 1,591 last year from 2,148 in 2005.
Amnesty International reported 1,591 executions last year.
It said 91 per cent of all known executions took place in six countries.
- China: More than 1,000 executions reported but actual figures could be as high as 8,000.
- Iran: 177 people at least, doubling the number in 2005.
- Pakistan: 82
- Iraq: 65, including at least two women - death penalty reinstated in 2004 to combat violence.
- Sudan: 65, chief among six African countries that carried out executions in 2006.
- United States: 53 people in 12 states, the only country in the Americas to have carried out any executions since 2003.
Khan said: "Africa, only six countries carried out executions in 2006. Belarus is the only country that continues to use the death penalty in Europe. The USA is the only country in the Americas to have carried out any executions since 2003."
Iraq joined the list of the world's principal executioners, Khan said. The televised hanging of Saddam in December "belied the reality that the execution rate in Iraq had dramatically escalated over the year with more than 65 hangings, of which at least two of those put to death were women".
Iran's executions doubled to at least 177 people, Pakistan put at least 82 to death and Sudan at least 65 but probably many more. Iran and Pakistan broke an international ban on executions of children as well. The United States executed 53 people.
China had the highest number of executions worldwide, with more than 1,000 recorded, though the precise number is a state secret and could be as high as 8,000, the rights group said.
However, Khan said officials in China and Iraq had "spoken of their desire to see an end to the use of the death penalty".
Death pentalty limits
Iraq re-introduced the death penalty in 2004 to combat violence. However, Iraq's human rights minister told the UN Human Rights Council in March that Baghdad could, as a first step, limit it to extreme cases like genocide and crimes against humanity.
With 19,000 people estimated to be on death row across the world, Khan called for a "universal moratorium".
Over 45 countries have abolished the death penalty for all crimes since 1990, showing progress toward worldwide abolition, Amnesty said.
In particular, 88 countries have abolished the death penalty for all crimes, 11 have abolished it for all but exceptional crimes, such as wartime crimes, and 29 countries have retained it in law but have not carried out any executions for the past 10 years or more, the group said.