US Secretary of State Condoleezza Rice is expected to make the announcement on Friday, The Washington Post said, adding that Rice's deputy Robert Zoellick worked out the details of the agreement at a meeting in Washington on Tuesday with British, French and German officials.
"We're in support of what the Europeans are doing, but we had to find a way to demonstrate it," a senior American official told The New York Times about the pending announcement. "This is our way of making clear that we will join the Europeans in giving Iran positive reasons to give up its program."
The New York Times said the US incentives -- support for Iran's entry into the World Trade Organization and selling Iran spare parts for its ageing commercial airliners -- would go into effect only if Iran agreed to permanently halt uranium enrichment at its nuclear plants.
Senior administration officials, quoted but not identified by both US dailies, told the Times that the United States does not plan to join the talks with Iran directly, leaving that to the Europeans.
Britain, France and Germany are trying to convince Iran to halt its work on the nuclear fuel cycle -- including the sensitive process of enriching uranium -- in return for a package of incentives covering trade, security and technology.
A new round of talks, the fifth since December, is to be held later this month, possibly in a capital of one of the three states negotiating for the European Union.
The United States maintains that Iran is trying to covertly develop nuclear weapons, while Tehran insists that its program is purely meant to meet civilian energy needs.
Citing an "unusual and extraordinary threat" from Tehran, US President George W. Bush on Thursday renewed sanctions that bar US firms and citizens from oil dealings with Iran.