At least 778 executions were known to have been carried out globally in 2013, 538 of them in Iran and Iraq alone, showed the 62-page report published on Thursday. It was up from 682 executions in 2012.

“The killing sprees we saw in countries like Iran and Iraq were shameful,” said Salil Shetty, Amnesty International’s secretary general.

“Only a small number of countries carried out the vast majority of these senseless state-sponsored killings.

“The long-term trend is clear – the death penalty is becoming a thing of the past. We urge all governments who still kill in the name of justice to impose a moratorium on the death penalty immediately, with a view to abolishing it.”

China is believed to have executed several thousand people – more than the rest of the world together – but exact figures are unavailable as Beijing authorities classify execution statistics as a state secret.

Iran officially acknowledged the execution of at least 369 people (55 more than in 2012) but activists say many hundreds more were put to death in secret, taking the actual number of executions in the Islamic republic close to 700.

Earlier this month, the UN secretary general, Ban Ki-moon, criticised Iran’s president, Hassan Rouhani, for his failure to reduce the country’s rate of executions. The UN chief said Rouhani’s new administration had not changed Tehran’s approach to the death penalty. Ahmed Shaheed, the UN special rapporteur for human rights in Iran, said that at least 176 people had been put to death since the beginning of 2014.

Those executed in Iran last year include Habibollah Golparipour, a Kurdish political prisoner convicted of the crime of moharebeh (waging war against God). Amnesty said he was given a death sentence in a trial that lasted only five minutes and was executed without prior notice to his family. It was not clear if he had access to a lawyer.

Iraq executed at least 169 people, an increase of almost a third from the previous year. Amnesty said many were executed on vague charges related to anti-terrorism laws.

Saudi Arabia acknowledged executing at least 79 people, of whom three were juvenile offenders, in defiance of international law. The US put to death 39.

Somalia executed at least 34, Sudan 21, Yemen 13, Japan eight, Vietnam seven and Taiwan six. Indonesia and Kuwait each executed five and South Sudan and Nigeria each four. Gaza executed at least three. Malaysia and Afghanistan each executed two people and India one.

Exact figures were unobtainable in a number of countries including North Korea and also in Syria where civil war prevents documenting such figures. Amnesty said it could not confirm how many people were executed in Egypt, which stunned the world by sentencing more than 500 people to death this week.

In Africa, Benin, Ghana and Sierra Leone took some promising steps towards ending the death penalty, but Somalia saw an alarming rise in its use of capital punishment, executing at least 34 people, up from six in 2012. In the Americas, the US is the only country that still uses capital punishment. More than third of its executions were carried out in the state of Texas.

Despite all this, Amnesty says the long-term trend continues to be one of a worldwide decline in the use of capital punishment. In 2013, 22 countries carried out executions (one more than the 21 countries in 2012), which is almost one in 10 countries in the world.

There were improvements, too. Belarus, which has not abolished the death penalty, did not implement any death sentences, making Europe and central Asia an execution-free zone last year. Gambia, the UAE and Pakistan, which had previously put people to death, also refrained from carrying out executions.

Saudi Arabia practiced beheading as a method of execution, while the US used electrocution. Hanging was used in a wide-range of countries such as Afghanistan, Japan, Kuwait, Malaysia and India. Iran was among the countries that carried out public executions, drawing much international condemnation. Lethal injection (in China and the US) and firing squad (in Somalia and Yemen) were among other methods.

A number of non-lethal crimes were punishable by death across the world, including drug offences, adultery, sodomy, blasphemy and pornography. North Korea is believed to have executed people for watching banned videos from South Korea.

More than 23,000 people were on death row by the end of last year and nearly 2,000 people were given death sentences in 57 countries in 2013.