US Secretary of State Condoleezza Rice

U.S. Secretary of State Condoleezza Rice says Iran could face additional sanctions if it defies a two-week deadline to respond to an international nuclear incentives package.

Rice, who spoke to reporters en route to the United Arab Emirates Monday, said Iran did not give a serious response to the package during nuclear talks with world powers in Geneva Saturday.  The incentives package is aimed at persuading Tehran to suspend sensitive nuclear activities.

Secretary Rice said Saturday's meeting sent a strong message that Iran will have to make a decision. But she warned that world powers are in the strongest possible position to return to sanctions if Iran does not act.

Rice is in Abu Dhabi Monday to meet with U.S. Undersecretary of State William Burns, who attended Saturday's talks in Geneva.  She is also expected to meet with foreign ministers from the Gulf and other allied Arab nations.

On Sunday, U.S. military chief Admiral Mike Mullen said he was encouraged by Saturday's nuclear talks.

The United States and its Western allies have accused Iran of working to produce a nuclear weapon.  Iran says its nuclear program is peaceful.

On Saturday, Iran again ruled out suspending its uranium enrichment program - a key demand of Western powers.  But Iranian President Mahmoud Ahmadinejad welcomed the Geneva talks as a step forward.  

Iranian and EU negotiators have agreed to meet again in two weeks.

Some information for this report was provided by AFP, AP and Reuters.