The U.S. and world powers had a secret deal with Iran to allow the Islamic Republic to dodge restrictions in last year's landmark nuclear deal, according to a new report from a Washington think tank.

Reuters first reported Thursday that the findings are based on information from several officials involved in the negotiations. The full details are contained in a report, obtained by Fox News, from the Washington-based Institute for Science and International Security.

Iran allegedly is not being held to the publicly announced conditions of the deal, which was supposed to allow a decade of inspections and transparency aimed at preventing Iran from developing nuclear weapons. The institute's president, David Albright, told Reuters that the “exemptions or loopholes are happening in secret, and it appears that they favor Iran.”

Albright had worked as an inspector with the UN International Atomic Energy Agency that investigated former Iraqi President Saddam Hussein’s nuclear weapons program, according to Reuters.

According to the report, some of the exemptions allowed Iran to exceed the limitations on how much low-enriched uranium could be kept at its nuclear facilities. The uranium can be configured into weapons-grade uranium. The report said that the U.S. and its negotiating partners -- Russia, China, Britain, France and Germany -- approved the exemptions.

The White House, though, pushed back. An official said the “United States and its partners did not and will not allow Iran to skirt its JCPOA commitments.

“Iran completed all of the steps required to get to Implementation Day under the JCPOA, as verified by the IAEA. Any assertion to the contrary is completely false, including any assertion that we moved forward with Implementation Day before Iran met all of its nuclear-related commitments.”

A senior official with knowledge of the deal, though, was cited in the report as saying that if the world powers didn’t allow these exemptions, then some of Iran’s nuclear facilities wouldn’t have been in compliance with the nuclear accord by the Jan. 16 deadline for Tehran to have its sanctions lifted.

However, according to Albright’s report, President Obama told Congress of the exemptions on Jan. 16, after they had already been granted. Congress was sent the confidential documents on the same day.

The White House has contended that Congress had been briefed “frequently and comprehensively” on the nuclear deal. Sen. Bob Menendez, D-N.J., told Reuters he had never received any briefings on the exemptions.

The world powers had also agreed to several other exemptions to help Tehran meet the relief deadline, including shipping 50 tons of material that could be used for nuclear weapons production to Oman, which the storage remained in Iranian control, according to the report.

Also, the world powers allowed Iran to operate 19 radiation containment chambers larger than the agreement had set. The chambers can be used to handle radioactive material.