WASHINGTON // UN investigators have identified a complex in Syria that increases suspicions the government worked with AQ Khan, the father of Pakistan's atomic bomb, to acquire technology that could be used to make nuclear arms.
The buildings in the north-west of the country closely match the design of a uranium enrichment plant provided to Libya when Muammar Qaddafi was trying to build nuclear weapons under Mr Khan's guidance, officials said.
The UN's International Atomic Energy Agency also obtained correspondence between Mr Khan and a Syrian government official, Muhidin Issa, who proposed scientific cooperation and a visit to Mr Khan's laboratories following Pakistan's successful nuclear test in 1998.
The complex, in Al Hasakah, now seems to be a cotton-spinning plant and investigators found no sign it was used for nuclear production.
But given that Israeli warplanes destroyed a suspected plutonium production reactor in Syria in 2007, the coincidence in design suggests that Syria may have been pursuing two routes to an atomic bomb - uranium as well as plutonium. Details of the Syria-Khan connection were provided by a senior diplomat with knowledge of IAEA investigations and a former UN investigator.
The Syrian government did not respond to a request for comment.
It has repeatedly denied pursuing nuclear weapons but has also stymied an investigation into the site bombed by Israel.
It has not responded to an IAEA request to visit Al Hasakah complex, the officials said.
The IAEA's examination of Syria's programmes had slowed as world powers focused on its uprising.
Syria has never been seen as being close to development of a nuclear bomb. There was also no indication that Damascus continued to work on a secret nuclear programme.
If Al Hasakah facility was intended for uranium production, the plans appear to have been abandoned and the path to a plutonium weapon ended with the Israel bombing.
But Mark Hibbs, an analyst at the nuclear policy programme at the Carnegie Endowment for International Peace, who has spoken to IAEA officials about Al Hasakah complex, said it was important to learn more about the buildings.
"What is at stake here is the nuclear history of that facility," Mr Hibbs said. "People want to know what did they intend to do there and Syria has provided no information."
Syria had reasons to seek a nuclear weapon. It has been in a Cold War for decades with Israel, believed to have a sizable nuclear arsenal.
"A nuclear weapon would give Syria at least a kind of parity with Israel and some status within the region," said Anthony Cordesman, a national security analyst at the Centre for Strategic and International Studies.
For years, there has been speculation about ties between the Syrian government and Mr Khan.
He supplied Iran with the basics of what is now an established uranium enrichment programme that has churned out enough material to make several nuclear weapons.
IAEA investigators homed in on Al Hasakah facility after a search of satellite imagery in the Middle East, which was sparked by a belief Mr Khan had a customer in the Syrian government.
The imagery revealed striking similarities to plans for a uranium enrichment facility that were seized during a Swiss investigation related to Mr Khan.
Another set of the same plans was turned over to the IAEA after Libya abandoned its nuclear programme.