More people were executed last year than at any point in the last 25 years, according to Amnesty International.
At least 1,634 people were executed in 2015, the highest number the rights group has recorded since 1989, according to new figures.
The group described the rise, documented in its Death Sentences and Executions report, released today, as "profoundly disturbing".
The steep rise in executions last year comes largely as a result of increases in the number of people executed in Iran, Pakistan and Saudi Arabia.
- According to Amnesty's figures, in 2015:
Amid the report's release, Amnesty International UK's director Kate Allen accused the government of "soft-peddaling" over the death penalty and seeming to make trade more important than human rights.
Her comments follow a similar criticism made by the the Commons Foreign Affairs Select Committee, which said there was "perception" the UK was prioritising trade and security with China, Saudi Arabia and Bahrain above human rights.
Ms Allen said: "Like the Foreign Affairs Committee yesterday, we're worried that the government has started soft-pedaling over foreign countries' use of the death penalty, preferring to prioritise trade with countries like China, Saudi Arabia or Pakistan."
Ministers, however, deny the issue of human rights has been downgraded in Britain's interaction with other states.
The Amnesty report also noted some positive developments on the death penalty during 2015 - Fiji, Madagascar, Republic of Congo and Suriname all abolished the death penalty, and Mongolia passed a new criminal code that will see the death penalty there abolished later this year.
According to the report, the top five executioners in the world in 2015 were China, Iran, Pakistan, Saudi Arabia and the USA.