Governments using executions to punish crime and "terrorism" are responsible for a 28% rise in death sentences worldwide, a report released by Amnesty International said.

The annual report, which was launched at a news conference in London, showed that despite a spike in the awarding of the death penalty, 22% fewer executions took place in 2014 than the previous year.

In 2014, an Egyptian court sentenced more than 500 members of the outlawed Muslim Brotherhood group to death, in what has become the largest mass death sentence in modern history.

Nigeria imposed 659 sentences last year, with some used to prosecute soldiers who had refused to participate in fighting militants Boko Haram.

Pakistan lifted a moratorium on the death penalty in December in response to the massacre of 141 people in a Peshawar school, hanging several militants believed to be responsible for the attack.

According to the report, the number of executions in the U.S. fell from 39 in 2013 to 35 in 2014, but the country faced condemnation for three botched executions using new methods to kill after a change in European Union policy on selling drugs believed to be used in the lethal injection.

Amnesty's report said that China was the worst offender worldwide, with the charity claiming it executes thousands but that the figures are kept a state secret.

140 countries have so far abolished capital punishment, with others looking set to follow in 2015.