U.S. Secretary of State Condoleezza Rice warned Iran on Wednesday not to delay talks aimed at ending its nuclear program.

"If indeed Iran is trying to stall, it's not going to work," Rice told reporters at a news conference with Turkey's Foreign Minister Abdullah Gul. "The international community has said that we need to get an answer, an indication of where Iran is going with this. We need to know if the path of negotiation is open or not."

Iran's top negotiator, Ali Larijani, postponed by one day talks scheduled for Wednesday with European Union foreign policy chief Javier Solana. There was no immediate explanation for the delay. Solana and Larijani were to discuss an incentives package put forward by the United States, Russia, China, Britain, France and Germany.

Rice said "a substantive response" from Iran was needed before the Group of Eight leaders meet later this month in St. Petersburg, Russia.

"It simply makes sense for the world to have some kind of indication of whether Iran intends to pursue the negotiated track or not," she said.