WASHINGTON, May 21: The United States has broken off its unofficial dialogue with Iran after blaming it for harbouring Al Qaeda leaders who planned last week’s suicide attacks in Saudi Arabia, US officials said on Wednesday.

Iran has denied sheltering Al Qaeda operatives and has described the US allegation as a campaign to malign Tehran without any basis.

But Defence Secretary Donald Rumsfeld rejected Iran’s denial and said that Iran was also hiding other Al Qaeda leaders, besides those responsible for planning suicide attacks in Riyadh that killed 34 people.

“Countries that are harbouring those terrorist networks and providing a haven for them are behaving as terrorists by so doing,” he told a Pentagon briefing.

Soon after Mr Rumsfeld renewed his attacks on Iran, officials in Washington said the United States was breaking off the unofficial dialogue it had been conducting with Iranian officials in Geneva.

The meeting between the two sides was due to have taken place in Geneva on Wednesday, which has now been cancelled.

The talks between Iran and the US began last month.