WASHINGTON >> The U.S. government is temporarily barring passengers on certain flights originating in eight other countries from bringing laptops, iPads, cameras and most other electronics in carry-on luggage starting tomorrow.

The reason for the ban was not immediately clear. U.S. security officials would not comment. The ban was revealed today in statements from Royal Jordanian Airlines and the official news agency of Saudi Arabia.

A U.S. official told The Associated Press the ban will apply to nonstop flights to the U.S. from 10 international airports serving the cities of Cairo in Egypt; Amman in Jordan; Kuwait City in Kuwait; Casablanca in Morocco; Doha in Qatar; Riyadh and Jeddah in Saudi Arabia; Istanbul in Turkey; and Abu Dhabi and Dubai in the United Arab Emirates. The ban was indefinite, said the official.

A second U.S. official said the ban will affect nine airlines in total, and the Transportation Security Administration will inform the affected airlines at 3 a.m. Eastern time tomorrow.

The officials were not authorized to disclose the details of the ban ahead of a public announcement and spoke on the condition of anonymity.

Royal Jordanian said cellphones and medical devices were excluded from the ban. Everything else, the airline said, would need to be packed in checked luggage. Royal Jordanian said the electronics ban affects its flights to New York, Chicago, Detroit and Montreal.

David Lapan, a spokesman for Homeland Security Department, declined to comment. The Transportation Security Administration, part of Homeland Security, also declined to comment.

A U.S. government official said such a ban has been considered for several weeks. The official spoke on the condition of anonymity to disclose the internal security discussions by the federal government.

Homeland Security Secretary John Kelly phoned lawmakers over the weekend to brief them on aviation security issues that have prompted the impending electronics ban, according a congressional aide briefed on the discussion. The aide was not authorized to speak publicly about the issue and spoke on the condition of anonymity.

The ban would begin just before Wednesday’s meeting of the U.S.-led coalition against the Islamic State group in Washington. A number of top Arab officials were expected to attend the State Department gathering. It was unclear whether their travel plans were related to any increased worry about security threats.

Brian Jenkins, an aviation-security expert at the Rand Corp., said the nature of the security measure suggested that it was driven by intelligence of a possible attack. He added that there could be concern about inadequate passenger screening or even conspiracies involving insiders — airport or airline employees — in some countries.

Another aviation-security expert, professor Jeffrey Price of Metropolitan State University of Denver, said there were disadvantages to having everyone put their electronics in checked baggage. Thefts from baggage would skyrocket, as when Britain tried a similar ban in 2006, he said, and some laptops have batteries that can catch fire — an event easier to detect in the cabin than in the cargo hold.

Most major airports in the United States have a computer tomography or CT scanner for checked baggage, which creates a detailed picture of a bag’s contents. They can warn an operator of potentially dangerous material, and may provide better security than the X-ray machines used to screen passengers and their carry-on bags. All checked baggage must be screened for explosives.