The United Nations nuclear agency announced Saturday afternoon that Iran has met the guidelines imposed in a nuclear deal between six world powers, a certification that frees Iran from economic sanctions and a freeze on billions of dollars of assets.

"Relations between Iran and the IAEA now enter a new phase," said International Atomic Energy Agency Director General Yukiya Amano. "It is an important day for the international community."

Inspectors' declaration Iran has disabled its nuclear infrastructure is the key step in a historic and controversial deal the United States and allies cut last year with Iran. The agreement lifts economic sanctions on Iran in exchange for the longtime pariah state's agreement to limit itself to a nuclear power program and give up pursuit of nuclear arms.

Certification by the IAEA that Iran has followed through on the July 14 nuclear deal allows Iran to reclaim $100 billion in assets frozen overseas by the U.S. and allies.

The White House immediately revoked executive orders from last summer that imposed the sanctions on Iran.

The action drew attacks by congressional Republicans and presidential candidates opposed to the deal.

"Today, the Obama administration will begin lifting economic sanctions on the world's leading state sponsor of terrorism. As the president himself has acknowledged, Iran is likely to use this cash infusion — more than $100 billion in total — to finance terrorists. This comes just weeks after Tehran's most recent illegal ballistic missile test, and just days after the IRGC detained ten American sailors," House Speaker Paul Ryan, R-Wis., said in a statement Saturday.

The influential American Israel Public Affairs Committee called implementation of deal Saturday "a turning point in Iran's strength as a terrorist state and in its ability to pursue regional dominance."

"Starting today, Iran can repatriate tens of billions of dollars from frozen foreign accounts, fueling its efforts to expand its reach across the region," AIPAC said. "The international community will dismantle its elaborate sanctions regime, and Iran will start down the path to legitimize its illicit nuclear program."

The group argued that Iran "brazenly violated mandatory United Nations Security Council resolutions by conducting prohibited ballistic missile tests" prior to the agreement.

The United States did not sanction Iran for those missle tests due to concern it would upset what were then secret talks on a prisoner swap to win the release of four dual American-Iranian citizens held in Iran, according to reports Saturday.

Although other sanctions against Iran are still in effect, the country will see additional benefits — including new oil, trade and financial opportunities — once western nations' sanctions are lifted.