The use of the death penalty is broadly diminishing around the world although a handful of countries that had not used capital punishment for several years resumed executions in 2012, Amnesty International said on Wednesday.

India, Japan, Pakistan and Gambia, all countries which had not put people to death for some time, resumed executions last year, and there was an "alarming escalation" in executions in Iraq, the rights group said in its annual survey of the death penalty.

London-based Amnesty said at least 129 people were executed in Iraq last year, almost double the 2011 figure of 68.

India carried out its first execution since 2004 when Ajmal Kasab, one of the gunmen involved in the 2008 Mumbai terror attacks, was hanged in November.

But the use of the death penalty continues to be restricted to an isolated group of countries, and progress towards its abolition was made in every region of the world.

A total of 21 countries were recorded as carrying out executions in 2012 - the same number as in 2011, but a sharp drop from 28 countries in 2003.

In 2012, at least 682 executions were known to have been carried out worldwide, two more than in 2011. At least 1,722 newly imposed death sentences in 58 countries could be confirmed, compared to 1,923 in 63 countries the year before.

But Amnesty stressed that its figures do not include the thousands of executions that it believes were carried out in China, where details are shrouded in secrecy.

"The regression we saw in some countries this year was disappointing, but it does not reverse the worldwide trend against using the death penalty. In many parts of the world, executions are becoming a thing of the past," said Salil Shetty, Secretary General of Amnesty International.

"Only one in 10 countries in the world carries out executions. Their leaders should ask themselves why they are still applying a cruel and inhumane punishment that the rest of the world is leaving behind."

China led the top five of countries using the death penalty, followed by Iran, Iraq, Saudi Arabia and the United States, with Yemen close behind.

Methods of executions in 2012 included hanging, beheading, firing squad and lethal injection. In Saudi Arabia, the body of one man executed through beheading was displayed in what is known as "crucifixion".

In Japan, three death row inmates were executed in March -- followed by another four later in the year -- ending a 20-month hiatus in executions there.

The United States remains the only country in the Americas to carry out executions -- the total number, 43, was the same as in 2011, but only nine states executed in 2012, compared to 13 in 2011. Connecticut became the 17th abolitionist state in April, while a referendum on the abolition of the death penalty was narrowly defeated in California in November.

China once again executed more people than the rest of the world put together, but due to the secrecy surrounding the use of the death penalty there it was impossible for Amnesty to obtain accurate figures.

Iraq was a black spot, and the start of 2013 holds out little promise of improvement.

Justice Minister Hassan al-Shammari said in March that Baghdad would continue to implement the death penalty, despite international calls for a moratorium.

Iraq has executed 29 people so far in 2013, according to an AFP tally, after executing at least 129 last year.

It announced in March that it executed a total of 18 people across two separate days -- March 14 and March 17. Al-Qaeda's Iraqi affiliate said that nationwide attacks on March 19 that left 56 people dead were "revenge for those whom you (the government) executed."

Amnesty did, however, note progress in Asia.

Vietnam did not carry out any death sentences, while Singapore observed a moratorium on the death penalty and Mongolia ratified a key international treaty committing the country to abolition.