The U.N. nuclear agency is expected Thursday to to deny an Iranian request to help complete a plutonium reactor over fears it could yield material for a nuclear weapon.

The top U.S. representative to the International Atomic Energy Energy, Gregory Schulte, said the expected decision on the Arak reactor near Tehran is due to - quote - "widespread mistrust of Iran's nuclear program."

Several developing nations support aid for the Arak reactor, but the United States and other Western nations oppose aid.

Iran has ignored earlier calls by the IAEA to stop building the reactor. Tehran says the Arak site will open in 2009, even without foreign aid.

In August, Iran defied a U.N. deadline to stop enriching uranium at a separate nuclear site.

Western nations are pressing for sanctions against Iran at the U.N. Security Council because of the decision. Iran says its nuclear program is for peaceful purposes.

Some information for this report was provided by AFP, AP and Reuters.