A surge in the number of executions recorded worldwide saw more people put to death last year than at any point since 1989, Amnesty International says.
At least 1,634 people were executed in 2015, a rise of more than 50% on the previous year, the group found in its review of the use of the death penalty.
Iran, Pakistan and Saudi Arabia were responsible for 89% of the executions.
The total does not include China, where Amnesty said thousands more were likely killed but records were kept secret.
Fiji, Madagascar, Congo-Brazzaville and Suriname changed their laws in 2015, while Mongolia also passed a new criminal code that will take effect later this year.