Iran''s top authority said the new U.S. administration was showing no sign of trying to correct its predecessor''s "big mistakes" in the region, in comments likely to disappoint Washington as it reaches out to Tehran.

Supreme Leader Ayatollah Ali Khamenei made the statement in a meeting with visiting Turkish President Abdullah Gul, whose country has said it was working to create "better understanding" between the United States and Iran, Iranian media reported.

In another verbal attack on Western policies, Iranian President Mahmoud Ahmadinejad told Gul and other regional leaders that the capitalist system was on the "verge of collapse" as a result of the global financial crisis.

"The liberal economy and the free market have failed," he said in a speech at a regional economic summit on Wednesday.

Iran, the world''s fourth-largest oil producer, initially said it was immune from the global financial crisis. But it is now facing falling revenue after oil prices plunged by $100 from $147 a barrel in July on weakening international fuel demand.

Ahmadinejad also dismissed the idea of Turkish mediation to improve relations with the United States, three days after Ankara said it would consider such a role.

He has previously said Tehran was ready for talks with its old foe but demanded a fundamental change in U.S. policy, and Wednesday''s remarks suggested he believed any such contacts should take place without go-betweens.