The US is reportedly investigating the possibility following the discovery of hundreds of special artillery shells, which Libya had filled with mustard gas.
According to Libyan officials, the shells were discovered in recent weeks at two sights in central Libya. US intelligence is leading a probe of the origin of the shells, the report added.
"We are pretty sure we know" that the shells were designed and produced in Iran and intended Libya, a senior US official told the newspaper.
Another US official told the Post there were "serious concerns" that Iran had provided such shells, adding that in all likelihood, the delivery took place "some years ago."
Potential evidence that Iran supplied the specialized shells could fuel further worries about Tehran's alleged pursuit of weapons of mass destruction.
The recent IAEA report into the Islamic Republic's nuclear aspirations strongly suggested Iran – despite its repeated denials – was researching nuclear weapons under cover of its civilian atomic activities.
On Sunday, Iran said it was ready to cooperate "further" with the UN atomic energy watchdog if it "balances its approach" to the Islamic republic, Foreign Minister Ali Akbar Salehi said, according to the ISNA news agency.
"We are prepared to cooperate with the agency more than ever, if the (UN) agency balances its approach and complies with its statutes and the safeguard agreements," Salehi was quoted as saying.
"If that is the case, we are prepared to cooperate much the same as before and even further with the agency," he said.
AFP contributed to this report
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