WASHINGTON - US authorities are planning to ban passengers traveling on certain US-bound foreign airline flights from carrying into the cabin larger electronic devices in response to an unspecified terrorism threat, US officials told Reuters on Monday.

The new rule is expected to be announced soon by the Department of Homeland Security, the officials said, adding that it had been under consideration since the US government learned of a threat several weeks ago.

A source said the rule would cover nearly a dozen foreign airlines. A separate government official confirmed an Associated Press report that the ban will impact 10 airports in eight countries in the Middle East and North Africa.

Reuters reported earlier that the ban would include airlines based in Jordan and Saudi Arabia. The officials did not name the other countries.

The officials said no American carriers were affected by the ban, which would apply to devices larger than a cell phone, and none travel directly to the airports impacted from US cities. Passengers would be allowed to carry larger devices in their checked luggage, such as tablets, portable DVD players, laptops and cameras.

Royal Jordanian Airlines said in a tweet on Monday that US-bound passengers would be barred from carrying most electronic devices aboard aircraft starting Tuesday at the request of US officials, including those that transit through Canada. Passengers can still carry cellphones and approved medical devices.

The Al Riyadh newspaper, which is close to the Saudi government, reported that the civil aviation authority had informed "airlines flying from the kingdom's (Saudi) airports to US airports of the latest measures from US security agencies in which passengers must store laptops and tablets" in checked-in baggage.

Al Riyadh quoted a civil aviation authority source as saying that these measures from senior US authorities were relayed to the Saudi interior ministry.

Saudia Airlines confirmed in a tweet that US transportation authorities had barred carrying larger electronic devices in cabin luggage.