The U.N. nuclear agency declared Iran had failed to halt nuclear work by a Thursday deadline, as the head of the IAEA Mohamed El Baradei and Iran's Ambassador to the IAEA Ali Asghar Sultanya attended the Comprehensive Nuclear-Test-Ban Treaty Organisation conference in Vienna on Thursday (August 31). Tehran defied the threat of sanctions by vowing never to abandon a programme the West fears could give it atom bombs. They both declined to comment on any issues related to the report. While addressing the conference, El Baradei said that Iran was one of the countries on the IAEA's agenda where they were working to establish the peaceful nature of their nuclear programme. "I think that this slow movement with regard to nuclear disarmament is having an impact on the first leg which I talked about the non-proliferation leg, our effect to make sure that no new countries will move to develop nuclear weapons. I'm sure that many of you are aware that we still having on our agenda, at least at the IAEA a couple of cases, where one of them, North Korea, said that they have developed nuclear weapons. Another Iran, where we are very much having work in progress to establish the peaceful nature of their programme. So we have challenges in the area on non-proliferation," El Baradei said as he addressed a conference on the CTBT. A confidential report of the Vienna-based International Atomic Energy Agency (IAEA), leaked to Reuters, said Iran resumed enriching small amounts of uranium in recent days. The agency said its probes had been blocked by lack of Iranian co-operation. The U.N. Security Council had asked Mohamed ElBaradei, to spell out on August 31 whether Iran had complied with the deadline set in a July 31 resolution. Iran's disregard of the Council's order to stop enriching uranium exposes it to possible sanctions and was widely expected after it opened a heavy water production plant on Aug. 26 and vowed not to mothball its nuclear programme. Washington said before the IAEA verdict became known that world powers were poised to begin discussing punitive measures against Iran next week. Iran vowed on Thursday never to shelve its nuclear programme, defying the threat of sanctions as a U.N. deadline fell due for Tehran to stop work that the West fears could lead to atomic bombs. In a televised speech earlier on Thursday, Iranian President Mahmoud Ahmadinehjad said Iran would not yield to pressure, defying the threat of sanctions as a UN deadline fell due for Tehran to stop work that the West fears could lead to atomic bombs. Iran says it wants atomic energy only for electricity, although it hid sensitive research from U.N. inspectors for almost 20 years and has hindered U.N. investigations since.