Secret Assad-era Syrian nuclear reactor was almost complete: UN

A near-complete nuclear reactor built secretly during the rule of toppled Syrian leader Bashar al-Assad would have been able to produce material to make nuclear weapons, the UN nuclear watchdog chief said on Monday.

Inspectors from the International Atomic Energy Agency (IAEA) last month visited two sites, one in Deir Ezzor and a second undisclosed location identified to them by Syrian authorities.

In a report seen by AFP last week, the IAEA said it found that Syria's previous government was building a nuclear reactor.

Assad was toppled in December 2024 and the current Islamist government came to power.

IAEA head Rafael Grossi said it was "obvious that the previous government was pursuing a number of clandestine" activities.

"They didn't want the world to know what they were doing," he told reporters after opening the Vienna-based agency's quarterly board of governors meeting.

"Given the configuration, the technical features of that type of reactor, this is a reactor that is very efficient in the production of fissile material that could be used directly for the fabrication of nuclear weapons," he said, adding that building the reactor was a "very important step".

He said the reactor -- which is currently being excavated -- "was almost completed".

It was "very possible... that the then Syrian authorities also performed some explosions in order to... hinder any possibility of an investigation," he added.

Besides the reactor under construction at the Deir Ezzor site, the IAEA found a fuel fabrication plant where nuclear fuel for the reactor was manufactured, and a location where nuclear fuel as well as uranium scrap and waste were stored.

In its report, the IAEA said it found around 73 tonnes of natural uranium metal.

Grossi has praised Damascus's "courageous decision" to report the undisclosed site.

The UN atomic watchdog had declared in 2011 that the location was "very likely" to host a nuclear reactor, adding that its information suggested it was being built with North Korean assistance.

On Monday, Grossi said it was up to the IAEA board to decide whether to close the file opened in 2011, adding that he currently had not been tasked to further investigate alleged connections to North Korea.

A draft resolution seen by AFP, expected to be submitted to the board this week for a vote, proposes closing the file.

The IAEA will continue to work with Syria to keep the material safe and report its findings, Grossi said.

The Institute for Science and International Security (ISIS), a US-based organisation specialising in nuclear proliferation, last week said questions remained.

"The new revelations (in the IAEA report) provide confirmation and new details... but they do not provide any surprises or fill in the missing information about the entire scope of the reactor and reprocessing project and Syria's cooperation with North Korea," it said.

Last month, Grossi visited the site in Deir Ezzor in the east, which has been shut for 18 years.

In 2018, Israel admitted carrying out a top-secret air raid on the site 11 years earlier.

In 2008, less than a year after the strike, US officials accused Syria of having sought to build a secret nuclear reactor and acknowledged that Israel had destroyed it in the raid.