"In the event Iran does not give an answer to the Security Council and does not comply with the conditions clearly enunciated by the Security Council, I think we'll want to move very quickly in the first part of September towards a debate in Security Council about sanctions, and they will be well deserved, because this has gone on a long time," US Undersecretary of State Nicholas Burns said.

U.N. resolution 1696 demanded Iran to suspend all uranium enrichment by the end of this month. However, Iran has rejected the U.N. resolution.

The United States has been accusing Iran of trying to develop nuclear weapons under the cover of civilian nuclear programs. Iran has insisted that its nuclear programs are for peaceful purposes only.