Iran will insert its first domestically-produced nuclear fuel rods into a research reactor in Teheran on Wednesday, a top Iranian official said on Tuesday.

"Because western countries were unwilling to help us, we began enriching uranium to 20 per cent to make nuclear fuel rods," Ali Bagheri, deputy chief of Iran's national security council, said in an interview here.

"These nuclear rods, the first created by Iranian specialists, will be inserted tomorrow (Wednesday) into the Tehran Research Reactor in the presence of Iranian President Mahmoud Ahmadinejad," Bagheri said on Tuesdsay.

Insertion of the domestically-produced nuclear fuel rods would mark a significant step forward in Iran's nuclear programme, experts said.

Ahmadinejad announced last weekend that Iran would make an "important" announcement about its nuclear program this week.

Iran says its nuclear program is confined to production of peaceful atomic energy which it says is a fundamental right of any country.

Western nations and Israel have charged that Tehran is secretly working to build nuclear weapons - an assertion Iran vehemently denies.