The total number of known executions carried out around the world in 2021 rose by 20% on the figure recorded for 2020, Amnesty International announced in Berlin on Tuesday.
The global human rights group attributed the rise in part to the easing of pandemic restrictions.
At least 579 executions were carried out in some 18 countries during 2021, it said, with Iran being responsible for at least 314. This represents a 28% rise from the 246 executions carried out by Iran in 2020.
There was a sharp rise of almost 40% in the number of death sentences passed in 2021, with Amnesty reporting a total of 2,052 handed down in 56 different countries.
Amnesty listed China, Iran, Egypt, Saudi Arabia and Syria as the countries with the highest known execution rates.
Thousands of death sentences believed to have been handed own and carried out in China were not included in the report, though China remains the country with the highest number of annual executions, according to the report.
State secrecy in North Korea and Vietnam, along with limited access to information in several other countries, continues to hinder a fuller assessment of the use of the death penalty, the report said.
Amnesty International Germany General Secretary Markus Beeko said a small group of states were responsible for "adhering to these cruel and inhumane killings, including Iran and Saudi Arabia, which greatly expanded state executions last year."
This trend was continuing into 2022, with Saudi Arabia executing 81 people on a single day in March, he noted.