More than 25 nations, including France, the UK and Canada, on Wednesday condemned the use of capital punishment by Iranian authorities, saying in a joint statement Tehran was executing protesters to "silence dissent".
The countries, joined by the European Union's top diplomat, "condemn in the strongest terms the ongoing executions of protesters and use of the death penalty" by Iran.
"The use of capital punishment to silence dissent, intimidate communities, and punish individuals exercising their human rights can never be justified," the statement said.
"The people of Iran must be free to exercise their rights to freedom of expression and peaceful assembly without fear."
Australia, New Zealand, Ireland, Germany and other European nations also joined the statement calling for Iran "to immediately end the use of the death penalty and release all those arbitrarily detained".
The statement joins growing alarm from the United Nations and rights groups over a surge in executions in recent months, after Iran was rocked by nationwide anti-government protests earlier in the year and the start of the Middle East war in February.
Earlier in August UN rights chief Volker Turk said the death penalty was being used by Tehran to "instill fear".
According to the UN, since March 19, at least 56 people have been executed on national security-related charges, including 27 people in cases linked to the protests.
More than 100 others are at risk of being put to death on similar charges, Turk said.
The UN and rights groups have warned of a lack of fair trials and forced confessions.
In late December last year, a protest movement initially sparked by the high cost of living exploded into widespread anti-government demonstrations.
Iranian authorities reported more than 3,000 deaths, but attributed the violence to "terrorist acts" orchestrated by the United States and Israel.
Rights groups based abroad recorded a far higher toll and said the security forces had fired on demonstrators.
The United States and Israel launched a joint attack on the country weeks later, on February 28, triggering the Middle East war.
Since then, arrests and executions have multiplied in the country, linked to both the conflict and the protests.
Last year, Iran put to death over 2,150 people, according to Amnesty International, making it again by a huge margin the world's most prolific executioner after China.
