Rights group Amnesty International says Iran and Iraq were responsible for a "sharp global spike" in executions last year.
Salil Shetty, Amnesty's Secretary-General, said the two states had indulged in a "virtual killing spree."
The findings of the annual report on the death penalty were presented on March 26 in London by Audrey Gaughran, director of global issues for Amnesty International.
"Almost 100 more people were put to death in 2013 compared to 2012. The countries responsible for that sharp spike are largely Iran and Iraq," said Gaughran.
According to the report, 169 people were put to death in Iraq -- the majority of those executed "convicted under vague antiterrorism laws."
In Iran, officially acknowledged executions had risen to at least 369 in 2013 -- from at least 314 in 2012, but Amnesty said at least another 335 executions had been reported to them by sources.
Gaughran said Hassan Rohani's presidency had not had any positive impact toward abolishing the death penalty.
"We haven't seen any positive developments since the new president came into office in relation to the death penalty," said Gaughran. "In fact we have seen, as this report highlights, an increase in executions in Iran this year. We are deeply concerned by a number of factors around those executions, including the fact that many of the trials are grossly unfair trials. Death sentences are given out for drug related offenses."
The report says 778 executions are known to have taken place globally in 2013, an increase of almost 15 percent on the previous year.
But Gaughran said: "The figure of 778 people executed does not include the thousands believed to be executed in China. Since 2009 Amnesty International has not published figures for the number of people executed in China because the death penalty is a state secret in China we are unable to confirm reliable figures."
The report did not include North Korea either, where the group said it was likely that far more executions were carried out than the 70 about which it had reliable reports.
Amnesty's Gaughran also criticized a ruling by an Egyptian court on March 24 that sentenced 529 members of outlawed Muslim Brotherhood to death for murder and other offenses.
Based on reporting by RFE/RL, AP, dpa, and AFP