Iranian Foreign Minister Mohammad Javad Zarif said US policies had turned the region into a powder keg, at a time when the Iranian president warned of countries "pumping huge sums to finance dirty wars in the region."

"The level of US arms sales is unreasonable and far exceeds regional needs," Zarif said. "This refers to the very dangerous policies pursued by Americans that do not support security, stability and peace in the Middle East."

For his part, Iranian President Hassan Rowhani condemned countries that said they were "pumping huge sums to finance dirty wars in the region."

Rohani said US sanctions against his country were "economic terrorism," stressing that "unfair and illegal US sanctions against the state of Iran targeted our country in a clear example of terrorism."

"Economic terrorism is designed to spread panic in a country's economy and fear other countries to prevent investment in the target country," he said.

5977126766001 93866d0c-544d-496d-84ad-de650cf44a33 e76d65be-12f1-429e-9d0a-436794df4a88
video

Warning of drugs
"I warn those who impose these sanctions that if Iran's ability to fight drugs and terrorism is affected, you will not be safe from the flood of drugs, seekers of asylum, bombs and terrorism," Rouhani said.

US President Donald Trump decided in May to withdraw from the multilateral nuclear deal with Iran and re-impose sanctions on its vital oil sector last month.

Drug trafficking poses a major challenge for Iran, on the border with Afghanistan, the world's largest producer of opium, as well as with Pakistan, a major drug transit country.

A United Nations report in 2014 showed Iran owes two-thirds of opium seizures and a quarter of heroin and morphine seizures worldwide in 2012.

"The fight against terrorism and extremism is a regional and international necessity," the Iranian president said at the opening of the second session of the six-nation conference, which includes Russia, China, Turkey, Pakistan, Afghanistan and Iran.