Iran's parliament speaker has urged lawmakers to decide on a landmark nuclear deal 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 Sunday that "the more it is delayed, it harms us."

He says the government had expected Washington take longer to approve the deal given opposition to it in the Republican-led Congress. 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 decide on the agreement in the coming days. Supreme Leader Ayatollah Ali Khamenei has said it is up to legislators to approve or reject the deal.