Six world powers started crucial talks with Iran on its nuclear program on Saturday.

The talks between Iran and the United Nations Security Council' s five permanent members plus Germany, known as P5+1, were held at Istanbul Convention Center in a bid to pressure Iran to suspend its controversial nuclear program.

The Iranian team was led by Saeed Jalili, secretary of Iran's Supreme National Security Council, while delegations of the six world powers were headed by EU foreign policy chief Catherine Ashton.

The talks came about 15 months after the last round of negotiations, which were held in Istanbul in January 2011, failed to reach any agreement.

The United States and its Western allies are expected to demand an immediate closure of the Fordo nuclear facility in central Iran and a freeze on the 20-percent uranium enrichment.

Jalili said earlier this week that his team intend to bring some "new initiatives" to the talks.