Iran's supreme leader Ayatollah Ali Khamenei has demanded concrete policy changes from the US as the price for new relations between the two states, BBC reported.

Ayatollah Ali Khamenei said he had seen no change in America's attitude or policy, singling out US support for Israel and sanctions against Iran. But he also said that if President Barack Obama altered the US position, Iran was prepared to follow suit.

President Obama on Thursday offered "a new beginning" in relations with Iran. He made the offer in a video message to Iran's leaders and people seen as a dramatic break with the approach of George W Bush's administration.

Speaking to a large crowd in the holy city of Mashhad, Ayatollah Khamenei said Iran had "no experience with the new American government and the new American president".

"We will observe them and we will judge," he said. "If you change your attitude, we will change our attitude."

In the speech, which was carried live by Iranian television, he said Iran was yet to see such a change.

"What is the change in your policy?" he asked. "Did you remove the sanctions? Did you stop supporting the Zionist regime? Tell us what you have changed. Change only in words is not enough."