By Frances Harrison
BBC News, Tehran
Iran has offered to send 20m barrels of crude oil to the US to help with the consequences of Hurricane Katrina.
The hurricane reduced US refining capacity by 10%
The two countries have had no diplomatic relations for decades, but America did send help to Iran when a severe earthquake hit Bam in 2003.
Speaking on state-run radio, Iran's envoy to OPEC said his country was ready to send up to five shiploads of crude oil to the US.
But he said this could only happen if US sanctions were lifted first.
The envoy, Hosein Kazempur-Arbedili, did not clarify if he meant lifted temporarily for this aid shipment, or permanently.
The idea behind this offer is that Hurricane Katrina has badly disrupted production in the Gulf of Mexico, which supplies up to a quarter of America's oil.
In practice, US sanctions may well mean Iran cannot carry through on its offer, but it is a rare gesture of good will.
When an earthquake devastated the Iranian city of Bam nearly two years ago a team of American doctors with medical aid was sent.
Though Iran was thankful for the humanitarian help it never led to a breakthrough in relations.