KONTAN.CO.ID - DUBAI. A fire at Iran's underground Natanz nuclear facility has caused significant damage that could slow the development of advanced centrifuges used to enrich uranium, an Iranian nuclear official said on Sunday.

Iran's top security body said on Friday that the cause of the fire that broke out on Thursday had been determined but would be announced later. Some Iranian officials have said it may have been cyber sabotage and one warned that Tehran would retaliate against any country carrying out such attacks.

On Thursday, an article by Iran's state news agency IRNA addressed what it called the possibility of sabotage by enemies such as Israel and the United States, although it stopped short of accusing either directly.

Israel's defence minister said on Sunday it was not "necessarily" behind every mysterious incident in Iran.

Three Iranian officials who spoke to Reuters on condition of anonymity on Friday said they believed the fire was the result of a cyber attack but did not cite any evidence.

"The incident could slow down the development and production of advanced centrifuges in the medium term ... Iran will replace the damaged building with a bigger one that has more advanced equipment," state news agency IRNA quoted the spokesman for Iran's Atomic Energy Organisation, Behrouz Kamalvandi, as saying.

"The incident has caused significant damage but there were no casualties."

Separately on Sunday, Iran's powerful Revolutionary Guards Navy chief said Tehran had built underground "missile cities" along the Gulf coastline and warned of a "nightmare for Iran's enemies".

Iranian authorities have said such sites exist in all provinces of Iran but have unveiled only three bases so far and not disclosed that they have been built along its coast.

Editor: Barratut Taqiyyah Rafie