PARIS: France said Thursday it was very concerned about Iran's "persistent refusal" to come clean about its nuclear programme, which the West suspects is aimed at producing an atomic bomb.

The comment came after talks with Iran failed yet again to reach a deal on enhanced inspections of Tehran's nuclear programme, two weeks before a major meeting with world powers.

"Iran's persistent refusal to finalise its discussions with the IAEA to be fully transparent about what its nuclear programme is aimed at is very worrying," said French foreign ministry spokesman Philippe Lalliot.

The International Atomic Energy Agency (IAEA) chief inspector said Thursday after returning from Tehran that he had not succeeded in getting Iran to grant access to sites, scientists and documents the agency believes may have been part of a covert nuclear weapons drive.

Iran says the IAEA's allegations are based on flawed Western and Israeli intelligence -- which it has not been allowed to see -- and says it has never sought to develop the bomb.

This latest failure comes less than two weeks before talks between Iran and six world powers -- the United States, China, Russia, Britain, France and Germany -- in Almaty, Kazakhstan on February 26.