By Patrick McLoughlin

STOCKHOLM, Nov 12 (Reuters) - Former chief U.N. weapons inspector Hans Blix cast doubt on Wednesday on charges that Iran engaged in a civilian energy programme to make a nuclear bomb, saying there was no direct evidence.

The United States has long accused Iran of using a nuclear energy programme as a front to build a bomb and is set to clash next week with three European countries over a U.N. report on the subject.

Blix, who is heading a new Swedish government-backed international commission on weapons of mass destruction, said Iran's civilian reactors were not themselves a worry and it was uncertain whether Tehran wanted to build a nuclear bomb.

"I haven't seen any evidence of that," he told Reuters in an interview at his Stockholm home. "I don't think these two reactors or a civilian nuclear programme are a danger per se."

Blix said many countries had similar programmes, but Iran still needed to reassure the world it was not moving towards a weapon.

His remarks came as President Mohammad Khatami voiced optimism that Iran would avoid being reported to the U.N. Security Council for possible sanctions, despite a tough U.N. report on its nuclear programme.

The International Atomic Energy Agency (IAEA) said in a report obtained by Reuters on Monday it found no evidence of a secret arms bid, but that Tehran had dabbled in activity often associated with bomb-making, such as plutonium production.

Western diplomats say the United States will have a tough fight getting France, Germany and Britain to back its position at a November 20 meeting of the IAEA board.

Washington wants the board to pass a resolution to report Iran to the Security Council, a move which could lead to sanctions.

Arms experts told Reuters the report supports U.S. claims Tehran has a secret atomic weapons programme by detailing a two-decade cover-up of research possibly linked to bomb making.

Looking at Iraq, Blix repeated his conviction that no evidence of weapons of mass destruction would ever be found.

While Washington was unlikely to pull out of Iraq soon -- despite potential political fallout ahead of 2004 presidential elections -- it would dearly love to leave, he said.

"I am sure they would like to get out, not only before an election, but any time American lives are lost. They thought Iraq would be an easy affair and people would greet them with flowers and hug them and it didn't turn out that way."

The credibility of politicians had been damaged, added the 75-year-old Swede, who left the U.N. inspectorate in June.

"So much of the evidence was so wrong. There were no direct lies but...they put a spin on it to try to convince the citizens that armed force was the only way to do it," he said.