Executions fell worldwide by nearly a third last year to their lowest levels in at least a decade, but several countries recorded a rise, Amnesty International said.

Use of the death penalty dropped in Iran -- by an eye-popping 50 percent, following a change to its anti-narcotics laws -- Iraq, Pakistan and Somalia, the rights group found in its annual review.

But it rose in Belarus, Japan, Singapore, South Sudan and the United States, while Thailand resumed executions for the first time in a decade and Sri Lanka threatened to follow suit.

In total, death penalty figures fell around the world from at least 993 in 2017, to at least 690 last year.