Iran detained the militants who sought refuge there after fleeing from Afghanistan Prince Saud told The Washington Post newspaper.
In an interview published on Sunday, Prince Saud said the Iranian authorities handed over the fighters in June, knowing that whatever intelligence was obtained from them would be passed on to the United States.
US President George W Bush has condemned Iran as being part of an "axis of evil", along with Iraq and North Korea.
The Bush administration played down the report, with one senior senator describing Iran's record on fighting terrorism as "not very good".
The US has accused Iran in the past of giving sanctuary to members of al-Qaeda.
US-Iranian 'co-operation'
"We asked (the Iranians) to hand them over and they did," Prince Saud told the newspaper.
Prince Saud also suggested that Iran had worked directly with America to combat al-Qaeda, but he declined to provide further details.
"The US and Iran can speak for themselves as to how much co-operation happened between the two countries," he said.
"Iran has not only co-operated with Saudi Arabia in this conflict in Afghanistan, but co-operated extensively with the United States," he said.
But, US Senator Fred Thompson, of the Senate Intelligence Committee, said the reports of help from Iran and Saudi Arabia were self-serving.
"This is one instance that serves the purposes of the Saudis and also the Iranians," he told a US television programme.
"But over a longer period of time, the track record has not been very good," he said.