VIENNA - UN nuclear inspectors on Friday delayed a trip to Iran after Tehran requested more time to prepare ahead of an October 31 deadline to prove it has no secret atomic weapons program.

The International Atomic Energy Agency (IAEA) said a team of inspectors who had been set to fly to Iran on Sunday would now leave sometime late next week.

"The Iranian government requested the delay to allow them more time to prepare for the visit," IAEA spokeswoman Melissa Fleming told Reuters.

The inspectors were headed to Iran as part of stepped up scrutiny by the IAEA ahead of an October 31 deadline for Tehran to enable the United Nations to verify it has no secret atomic weapons program.

After strong lobbying by the United States for action, the IAEA governing board on September 12 set the deadline and called on Tehran to suspend all uranium-enrichment activities.

Iran insists its nuclear ambitions are limited to generating electricity.