The United States confirmed on Wednesday that it received an offer of assistance from Iran in the aftermath of Hurricane Katrina.
"I guess we received this offer, with some political conditions attached to it, through the press," State Department spokesman Sean McCormack said at a briefing.
"We have not received a formal offer via the Swiss channel from the Iranian government," the spokesman said.
According to US media reports, Iran offered to send the United States 20 million barrels of crude oil in the aftermath of Hurricane Katrina on condition that Washington waives trade sanctions on Teheran.
The United States severed diplomatic relations with Iran after Iranian militants stormed the US embassy in Teheran and held 52 American hostages in 1979. Washington then imposed trade sanctions on Iran.