Saudi Arabia has engaged in “many deeply troubling actions and statements that have provoked alarm in Congress,” Senators Bob Menendez, a Democrat, and Marco Rubio, a Republican, told Perry in a letter, a copy of which was seen by Reuters.

The senators said Congress was beginning to reevaluate the U.S.-Saudi relationship, and they believe Washington should not be providing nuclear technology or information to Saudi Arabia now.

The Trump administration has been quietly negotiating a deal that would potentially help Saudi Arabia build two reactors.

Last week news reports revealed that since November 2017, Perry has authorized so-called Part 810 approvals allowing U.S. companies to share sensitive nuclear information with the kingdom. The approvals were kept from the public and from Congress.

The senators asked Perry to provide them by April 10 with the names of the companies that got the 810 approvals, what was in the authorisations, and why the companies asked that the approvals be kept secret. U.S. Representative Brad Sherman, a Democrat, also asked the Energy Department in a separate letter what was in the approvals.

While 810 agreements are routine, the Obama administration made them available for the public to read at Energy Department headquarters. Lawmakers say the department is legally required to inform Congress about the approvals.

Perry approved the seven recent authorisations as the administration has tried to hash out nonproliferation standards with Saudi Arabia. Such a pact, known as a 123 agreement, would have to be agreed before U.S. companies can share physical exports of materials and equipment to build reactors.

The kingdom has resisted standards on reprocessing spent fuel and enriching uranium, two potential paths to making nuclear weapons.

The United States has been competing with South Korea, France, Russia and China on a potential deal to help build reactors in Saudi Arabia. The kingdom is expected to announce the winner this year.

Lawmakers from both parties have been concerned about Saudi Arabia’s bombing campaigns in Yemen, which is on the brink of famine, and the killing of journalist Jamal Khashoggi, a U.S. resident, last October in the Saudi consulate in Istanbul.

Concern in Congress grew last year after the kingdom’s Crown Prince Mohammed bin Salman told CBS that “Saudi Arabia does not want to acquire any nuclear bomb, but without a doubt if Iran developed a nuclear bomb, we will follow suit as soon as possible.”

Perry has said the 810 approvals were kept from the public for corporate proprietary reasons.

He has also said that if Saudi Arabia relies on China or Russia for building nuclear reactors those two countries don’t give a “tinker’s damn” about non-proliferation.

Many non-proliferation experts dispute the notion that a deal with China or Russia would be riskier. These people say the United States has many other levers it can pull to influence nuclear behaviour.

At another Senate hearing, the five members of the Nuclear Regulatory Commission, including Chairman Kristine Svinicki, would not say whether the NRC raised any concerns over the 810 approvals in a required consultation with the Energy Department. Svinicki said the NRC’s consulting role on the approvals is narrow and delegated to staff.

Senator Chris Van Hollen, a Democrat who asked the question of the NRC at the hearing, told Reuters in an interview that the commissioners’ lack of knowledge about the approvals was “stunning.”

“It’s kind of scary because we do rely on them to provide input into this process and not a single commissioner knew anything about what input they may or may not have provided.”