With deadlines approaching, the State Department on Tuesday said it has seen no indications that Iran plans to comply with U.N. demands that it suspend enrichment of uranium, a key step in making nuclear weapons.
Defiance could trigger efforts by the United States and European allies to impose economic or political sanctions on Iran in the Security Council.
Secretary of State Condoleezza Rice, due in New York this week to oversee U.N. attempts to bring about a cease-fire in the Mideast, will also confer with foreign ministers about how to deal with Iran, said the State Department spokesman Sean McCormack.
"There have been a variety of public statements from the Iranians, but we haven't seen any evidence yet that they are complying with the demand and requirement of the international community," McCormack said.
World powers in June offered Iran a package of incentives to curb its enrichment program. These included the United States supplying Iran with some nuclear technology for civilian projects.
Iran denies that is developing nuclear weapons, describing its enrichment and related activities as civilian in nature.
The U.N. Security Council on July 31 passed a resolution giving Iran until Aug. 31 to suspend enrichment or face the threat of economic and diplomatic sanctions.
Iran has promised a response by Aug. 22, although it vowed last Sunday to expand uranium enrichment "where required."