Mehr said the two men would "examine solutions to Afghanistan's problems" as Iran seeks to boost relations.

The United States has made a number of efforts to involve all of Afghanistan's neighbors, including Iran, in restoring stability to Afghanistan.

But they have been complicated by the lack of diplomatic relations between Tehran and Washington and the standoff over Iran's nuclear programme.

Ahmadinejad on Saturday called the official version of the Sept. 11 attacks a "big lie" used by the US as an excuse for the war on terror, state media reported.

"September 11 was a big lie and a pretext for the war on terror and a prelude to invading Afghanistan," Ahmadinejad was quoted as saying by state TV. He called the attacks a "complicated intelligence scenario and act." The Iranian president has questioned the official US version of the Sept. 11 attacks before, but this is the first time he ventured to label it a "big lie."

In 2007, New York officials rejected Ahmadinejad's request to visit the World Trade Center site while he was in the city for a UN meeting. The president also sparked an uproar when he said during a lecture in New York that the causes and conditions that led to the attacks, as well as who orchestrated them, still need to be examined.

At the time, he also told Iranian state TV the attacks were "a result of mismanaging and inhumane managing of the world by the US" and that Washington was using Sept. 11 as an excuse to attack others.