The US Secretary of State, Condoleezza Rice, has said Iran has said nothing to suggest it plans to suspend uranium enrichment.
Speaking to reporters at Shannon Airport during a stopover to the Middle East, Ms Rice said foreign ministers of the five permanent members of the United Nations Security Council and Germany might meet later this week to discuss Iran's nuclear programme.
The Security Council has threatened to impose sanctions on Iran if it fails to suspend its enrichment of uranium, a process that can produce material for atomic weapons.
Iran denies it is developing nuclear weapons.
The foreign ministers held a conference call over the weekend to discuss European Union foreign policy chief Javier Solana's efforts to coax Iran into suspending enrichment.
'I think it's fair to say that we have not yet heard anything that suggests that the Iranians are going to suspend,' Ms Rice said, noting that Iran's President Mahmoud Ahmadinejad was recently quoted as rejecting any suspension.
Even though Iran has failed to meet the Security Council's demand that it suspend its nuclear activities by 31 August, it is not certain that the major powers will move to impose sanctions.
Russia and China, which hold vetoes on the UNSC, both have had misgivings about the use of sanctions.