TEHRAN, Iran -- Iran's parliament speaker on Sunday urged lawmakers to decide on a landmark agreement reached with world powers that would curb Tehran's nuclear activities in exchange for the lifting of international sanctions.

The official IRNA news agency quoted Ali Larijani as telling members of parliament that "the more it is delayed, it harms us."

Supreme Leader Ayatollah Ali Khamenei, who has final say on all state matters, has said it is up to legislators to approve or reject the deal. It's not clear whether parliament will hold an up-or-down vote on the agreement, or whether a majority of lawmakers support the deal.

Larijani said Iran had expected Washington take longer to approve the deal given opposition to it in the Republican-led Congress. However, U.S. President Barack Obama won enough Democratic support to prevent Congress from derailing the agreement or forcing him to use his veto.

Iran's parliament is expected to enter final discussions on the agreement next week.

A special parliamentary committee that is in charge of reviewing the deal has urged the government to stand firm in its refusal to allow inspectors to visit military sites or interview nuclear scientists.

Western nations have long suspected Iran has secretly pursued nuclear weapons alongside its civilian program. Iran denies the allegations, insisting its program is devoted to peaceful purposes such as power generation and cancer treatment.