Iran atom progress "slow but steady" - ex-IAEA aide

VIENNA (Reuters) - Iran is making steady progress in its nuclear enrichment programme but there is still time to find a diplomatic solution over work the West fears is aimed at making bombs, a former top U.N. nuclear official said.

Olli Heinonen, who stepped down in August as chief of U.N. nuclear inspections worldwide, also voiced doubt about reports that Iran's atomic activities were the target of a cyber attack.

Security experts say the release of the Stuxnet computer worm may have been a state-backed attack on the Islamic Republic's nuclear programme, most likely originating in the United States or Israel.

Some analysts believe Iran may be suffering wider sabotage aimed at slowing its nuclear advance, pointing to a series of unexplained technical glitches that have cut the number of working centrifuge machines at the Natanz enrichment plant.

Heinonen said the Stuxnet virus, which Iran said had hit computers used by nuclear staff, had also been discovered in other countries so he found it a "bit hard to believe" it had been specifically aimed at Iran's Bushehr atomic plant or Natanz.

"This is all speculation until the facts are found," he told Reuters in a telephone interview on Thursday.

Asked if there had been any indications of past sabotage aimed at Natanz, he said: "I don't think there is enough technical evidence to say -- yes, there has been sabotage (or) no, there has been no sabotage."

Heinonen noted that Iran's monthly output of low-enriched uranium, which can fuel power plants or provide material for bombs if refined much further, had been stable at about 120 kg.

"Let's assume some machines are failing, the others are then performing better," the Finnish nuclear expert said.

"CLOCK IS TICKING"

Analysts say about 1,000 kg may be enough for a bomb, if that is Iran's intention. The International Atomic Energy Agency (IAEA), Heinonen's former employer, said last month Iran had accumulated about 2.8 tonnes of the material.

Until he stepped down for personal reasons, Heinonen was deputy director-general of the U.N. agency and head of its nuclear safeguards department, which verifies that countries' nuclear programmes are not being diverted for military use.

He was one of the IAEA's leading experts on Iran, which denies its nuclear programme is aimed at making bombs despite intelligence indications to the contrary, which he investigated for years.

Heinonen, who is now a Senior Fellow at Harvard University's Belfer Center for Science and International Affairs, described Iran's overall progress on its enrichment programme as "slow but steady" and it had not yet reached the mass production stage.

"However, the clock is ticking. They are making progress, but I think there is still time for a negotiated solution."

World powers hope that new U.N., U.S. and European sanctions imposed on Iran since June will persuade it to enter negotiations on its nuclear programme which the West hopes will lead to a suspension of all uranium enrichment activity.

Iran, which says its nuclear work is aimed at generating electricity, has repeatedly ruled out halting enrichment.

Heinonen said only the Iranians themselves really knew what their aims were with the nuclear programme.

"It has to do with prestige, it has to do with their own security, to be a regional player, it is a complex thing," he said about Iran's motivations. "It is not just about, let's say, nuclear weapons or to produce fuel for Bushehr."