Iran is still not cooperating with efforts to resolve outstanding questions regarding its nuclear programme, International Atomic Energy Agency chief Mohamed ElBaradei said on Tuesday.

The head of the U.N. nuclear watchdog repeated that Iran was meeting its obligations to allow inspectors into nuclear sites, but the lack of cooperation regarded questions on past activities.

"Iran right now is not providing any access or any clarification with regard to those studies or the whole possible military dimension," ElBaradei said in Paris at a media event.

"No, I'm not obviously happy with the degree of cooperation. They shut off any cooperation with the agency over the past few months," he said.

Iran has been pressing ahead with expanding its ability to enrich uranium which can be used to fuel power plants, or potentially nuclear weapons.

But ElBaradei said Iran hadn't added any further centrifuges to refine enriched uranium.

"They haven't really been adding centrifuges, which is a good thing," he said. "Our assessment is that it's a political decision."

The IAEA said in its latest report in November that Iran had not boosted the number of centrifuges regularly refining uranium since reaching a level of 3,800 in September.

Turning to the subject of an alleged reactor site in Syria that was destroyed in an Israeli air raid in 2007, ElBaradei repeated that samples from the site were not conclusive and called for greater cooperation from the Syrian authorities.

ElBaradei had said in November that uranium traces found at the Syrian site were not sufficient evidence of undeclared nuclear activity but Syria should be more open to help clarify the issue.