The United States and four other permanent members of the UN Security Council and Germany are considering new sanctions against Iran after Tehran failed to give clear answer to an incentives package by the six major powers, the State Department said Wednesday.

"We are very disappointed that Iran has failed yet again to give ... a clear answer to the P5+1 generous incentives package. The letter we received yesterday appears to be a stalling tactic," State Department spokesman Gonzalo Gallegos said.

Due to this reason, Gallegos said, "The P5+1 (major powers) are discussing next steps in the UN Security Council and beginning to consider possible outlines of another sanctions resolution."

Gallegos made the remarks after the United States, Britain, France, Russia, China and Germany, who have been working together for the settlement of Iran's nuclear program, held a conference call Wednesday after Tehran failed to give a clear answer to an incentives package by the six countries.

The spokesman declined to comment the a building new sanctions against Iran, saying "I am not going to guess how long this will take and where it may ultimately lead."

The UN Security Council has imposed three sanctions resolution against Tehran's nuclear program since December 2006, demanding a halt of the uranium enrichment work. However, Iran has repeatedly turned down the request.

On July 19, European Union foreign policy chief Javier Solana and Iran's top nuclear negotiator Saeed Jalali held nuclear talks in Geneva over Tehran's disputed nuclear program. U.S. Undersecretary of State William Burns attended the meeting.

During the one-day meeting, Iran failed to give a clear answer to the package of incentives proposed by six major countries -- the United States, Britain, France, Russia, China and Germany, requiring the country to suspend its nuclear enrichment program in exchange for political and economic benefits.

Iran was expected to give final response to the incentives offer on Aug. 2. Tehran, which rejects the two-week deadline for response to the package, delivered a letter from Iranian Foreign Minister Manouchehr Mottaki to Solana on July 4, which did not mention nuclear suspension.

The United States and its Western allies criticized Iran for its evasive answer to the offers by the six major countries, and warned that if no positive response is delivered by Tehran, there will be no choice but to ask the United Nations to proceed with further sanctions.

The United States and its allies have accused Iran of developing nuclear weapons, but Iran insists that its nuclear program is only for peaceful purposes.

Editor: Yan