WASHINGTON - The White House on Thursday released a summary of the deal reached between six major world powers and Iran to curb its nuclear program, responding to calls from the US Congress and other groups for more transparency about what the agreement entails.

Iran has denied it wants to use the program to eventually build nuclear weapons but agreed to scale it back after the international community applied strict financial and oil sanctions.

The six-month preliminary deal includes some relief from the sanctions as talks continue toward a broader, long-term deal.

The White House gave Congress access to the full text of technical instructions for the International Atomic Energy Agency (IAEA) but released a detailed four-page summary of the deal to the public.

"It is the preference of the IAEA that certain technical aspects of the technical understandings remain confidential," White House spokesman Jay Carney said.

Wendy Sherman, the State Department's lead Iran negotiator, briefed lawmakers on the agreement on Thursday. Some walked out of the meeting saying it had heightened, rather than eased, their concerns about negotiations between Iran and the United States and five other world powers.

"I'm more disturbed more than ever after the briefing," Republican South Carolina Senator Lindsey Graham told reporters. Graham, a frequent critic of Obama administration foreign policy initiatives, is a co-sponsor of a bill opposed by the Obama administration to slap new sanctions on Iran if it walks away from the negotiations.

VERIFICATION

Iran agreed to stop production of 20 percent enriched uranium on or by Monday, January 20, and to begin diluting half of its stockpile of 20 percent enriched uranium.

Over the next six months, the IAEA will verify a series of other curbs on enrichment and use of centrifuges. Iran is not allowed to commission or fuel the Arak reactor, and must stop producing and testing fuel for the reactor, the summary said.

At the end of the six-month period, Iran will agree to "a cap on the permitted size of Iran's up to 5 percent enriched uranium stockpile," the summary said.

IAEA inspectors will visit the Natanz and Fordow uranium enrichment sites daily, including both scheduled and unannounced inspections. Inspectors will visit the Arak reactor at least monthly, up from the current pace of one every three months, or longer.

Iran agreed to provide design information for the Arak reactor and other access to related facilities, the summary said.

The added inspections will "enable the international community to more quickly detect breakout or the diversion of materials to a secret program," the summary said.

The European Union, Iran, and the six major powers (P5+1) that are part of the agreement will name a joint commission of experts to work with the IAEA to implement the deal and discuss any issues that arise. The group will meet once a month.