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Iran could be on track to execute more than 1,000 people this year, even as it seems more willing to engage with world powers, a United Nations investigator said Monday.

U.N. special rapporteur on Iran, Ahmed Shaheed, suggested that human rights violators should be named and shamed and targeted with sanctions such as a travel ban.

Shaheed described his latest report to the United Nations as "marginally more optimistic than my previous reports" and told reporters he had witnessed more "meaningful" engagement between Iran and the U.N.

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He said he met for the first time with members of the Iranian judiciary and security forces in Geneva last month. "Their response to my current report has been the most substantive over the past 4-1/2 years," he said.

However, some 700 people have already been executed in Iran in 2015 and the country is "possibly on track to exceed 1,000 by the end of the year," Shaheed said. He has reported that at least 753 people were executed in Iran in 2014.

Iranians watch the execution of two men in 2013. Ebrahim Noroozi / ASSOCIATED PRESS, file

He also criticized Tehran for jailing some 40 journalists during the year for vague charges.

His comments echo an August report by U.N. Secretary-General Ban Ki-moon which said promises of greater freedoms for Iranians have not resulted in any major improvements in human rights and freedom of expression.

"The nuclear agreement reached this summer presents opportunities for advancing human rights in the country," said Shaheed, adding that ending sanctions on Iran would have a direct impact.

Under the July 14 agreement between Tehran and six world powers, economic sanctions on Iran will be lifted in exchange for curbs on its nuclear program.

Iran's U.N. mission did not immediately respond to a request for comment.