A senior council of Iranian clerics and lawyers on Wednesday approved implementing a landmark nuclear deal with world powers, sealing the final requirement in the process despite hard-liners' efforts to derail it.

The Guardian Council's vote, while apparently not unanimous, marks a major victory for the administration of moderate President Hassan Rouhani, which has campaigned on easing tensions with the West.

But it comes as Iran's powerful Revolutionary Guard publicized images of an underground missile base and also has fired off a new long-range surface-to-surface rocket, showing hard-liners will remain a potent force within the Islamic Republic.

Iranian state television announced the decision by the Guardian Council, one of the top leadership bodies in Iran's cleric-ruled system. The 12-member council, half appointed by Iran's Supreme Leader Ayatollah Ali Khamenei and half by the country's judicial chief with parliament's approval, must sign off on all bills before they become law.

Nejatollah Ebrahimian, the council's spokesman, said the body approved the parliamentary bill implementing the deal "by an absolute majority of the votes." He did not offer a voting breakdown. The council meets behind closed doors.

Some council "members raised objections to the bill and found it contrary to the constitution. There were debates," state television quoted Ebrahimian as saying. "At the end, a majority of the council members voted that the parliamentary legislation is not against the constitution and Shariah law."

Hard-liners had hoped to stall the deal in order to weaken Rouhani's administration ahead of February's parliamentary elections. But many in Iran applauded the final nuclear deal, struck July 14 in Vienna, as it lifts crippling economic sanctions in exchange for limits on the country’s nuclear program.

On Tuesday, hard-line lawmakers shouted, scuffled and wept during a final parliamentary hearing on the bill, but 161 lawmakers voted for it while 59 voted against it and 13 abstained. Another 17 did not vote at all, while 40 lawmakers did not attend the session.

The council's decision marks the last approval needed before starting the deal, which came after nearly two years of negotiations between Iran and the United States, Britain, France, Russia, China and Germany. The U.N. Security Council previously approved the deal on July 20 and the U.S. Congress blocked efforts by Republicans to derail the accord in September.

The Iranian bill grants responsibility for implementing the deal to Iran's Supreme National Security Council, the top security body of the country, which Rouhani heads. It allows Iran to withdraw from the agreement if world powers do not lift sanctions, impose new sanctions or restore previous ones.

The bill also requires the Iranian government to work toward the nuclear disarmament of Israel, which has the region's sole, if undeclared, nuclear arsenal. It also bans Iran from producing or deploying its own nuclear weapons, while urging its officials to take "necessary measures" to prevent the U.S. and the West from penetrating the country, a concern mentioned by Khamenei in recent weeks.

Provided Khamenei does not openly oppose the bill, analysts expect Iran to begin shutting down parts of its nuclear program in the coming weeks.

Iran’s Parliament Speaker Ali Larijani heralded the agreement as a sign of Tehran’s triumph over sanctions and what he called attempts to “trample on the rights of the Iranian nation for the past 12 years, resorting to the language of threat and pressure,” Iran’s official Islamic Republic News Agency (IRNA) reported.

“We had no way but to resist, and the blessings of resistance was we finally managed to achieve a satisfactory status with the West regarding the national nuclear program.”

During the months after the deal was reached, Khamenei did not publicly say whether he endorsed or opposed it. However, he repeatedly commended Rouhani’s negotiating team during the talks, even as hard-liners criticized the diplomats for giving away too much.

Despite the victory, Rouhani and his allies still face challenging times ahead. Before the announcement of the council's decision, state television aired footage of a Guard underground missile base, saying it was one of hundreds around the country. It didn't disclose the location but said it was 1,600 feet underground.

This base "is an iceberg floating around that only has its tip out of the water," said Amir Ali Hajizadeh, head of the Guard's aerospace branch, during the broadcast. "We have so many bases that [our enemies] cannot confront those bases, no matter how many bases they identify."

The base tour follows an announcement about a new locally made torpedo and the firing Sunday of a new ballistic missile. The U.S. has said it would raise the missile test at the U.N. The White House has said it believed there were "strong indications" that Iran violated Security Council resolutions with the launch.

Al Jazeera and wire services