Executions in Iran have been rising at "an exponential rate" since 2005 and could top 1,000 this year as the country cracks down on drug offenders, a U.N. investigator said Tuesday.

Ahmed Shaheed said in a report to the General Assembly and at media briefings that Iran executes more individuals per capita than any other country in the world.

He said the majority of executions violate international laws that ban the use of capital punishment for non-violent offenses and for juveniles. He urged Iran to impose a moratorium on the death penalty in those cases, and for all but the "most serious crimes" where it can be shown there was an intention to kill that resulted in the loss of life.

Shaheed, the special investigator on the human rights situation in Iran, said the "shocking 753 executions" carried out by Iran in 2014 — the highest number ever — will be topped this year.

In the first seven months of 2015, at least 694 people were reportedly executed by hanging, he said, and a number of human rights organizations now report that well over 800 individuals have been executed in the last 10 months. "And there are dozens more waiting a similar fate on death row," he added.

Shaheed called the rate of executions "alarming" and said Iran is "possibly on track to exceed 1,000 by the end of the year."

He said 69 percent of the executions during the first six months of 2015 were reportedly for drug-related offenses, reflecting the increasing influx of drugs and rising drug abuse in the country.

The government view, Shaheed said, is that the effects of drug trafficking on the health and security of the Iranian people make drug-related offenses "most serious" crimes that deserve to be considered capital offenses — though he said the authorities denied a majority of the executions documented by human rights organizations and requested proof.

While Shaheed said the overall human rights situation in Iran remains "dire," he said his latest report is "marginally more optimistic than my previous reports."

For the first time, he said he met with Iranian judicial, human rights, foreign affairs and narcotic officials in Geneva on Sept. 15-16 to discuss the gravity of the drug problem and the government's response. He called the government's engagement with him "more substantive," but stressed that none of the U.N. special investigators on rights issues have visited Iran since 2005.

He said the nuclear deal between Iran and six world powers reached in July and the lifting of economic sanctions that is expected to follow "can potentially have a beneficial multiplier effect on the human rights situation in the country, especially on the enjoyment of economic and social rights."

Shaheed urged continuing support for President Hassan Rouhani's government to strengthen protections for fundamental rights and improve laws but he said reforms require support from all branches of the government and state.

"Therefore, it is my sincere hope that Iranian officials will come together with the same constructive spirit that resulted in the nuclear agreement to address the serious rights abuses taking place in the country today," he said.

Shaheed cited Iran's reported use of prolonged solitary confinement, and torture to obtain confessions.

He blamed the troubling state of human rights in Iran today largely on "a deeply flawed justice system," including the lack of access to lawyers and the criminalization of the right to freedom of expression which has seen the arrest of 46 journalists as of April and extremely harsh sentences for individuals using social media to discuss views on the government and human rights.

"Some have even received death sentences simply for posting articles on Facebook and other social media sites," he said.