Four airports remain under a ban for carry-on laptops on US-bound flights, imposed amid fears that IS is developing a bomb concealed in personal electronics.

Washington: Four airports remain under a ban for carry-on laptops on US-bound flights, imposed amid fears that Islamic State is developing a bomb concealed in personal electronics, officials said Tuesday.

The ban remains in place for Saudi Arabia's two main international airports, in Riyadh and Jeddah, as well as Egypt's Cairo International and Morocco's Casablanca Mohammed V International Airport, the Department of Homeland Security said.

Six others across the Middle East have been removed from the ban, originally put in place on 21 March, after improving security procedures. The ban requires travellers to pack all personal electronic devices larger than cellphones in luggage stored in the aircraft's baggage compartment. The move came after intelligence officials learned of efforts by the Islamic State group to fashion a bomb into consumer electronics.

The original ban was focused on airports in the Middle East and North Africa.

But in June, DHS issued directives to 180 carriers around the world flying into the United States mandating improvements in security procedures, especially physical and technological screening of baggage and electronics.

The directives included pressure to install explosive-detecting scanners within weeks, as well as adding more bomb-sniffing dogs.

"I am concerned that we are seeing renewed interest on the part of terrorist groups to go after the aviation sector — from bombing aircraft to attacking airports on the ground, as we saw in Brussels and Istanbul," said Homeland Security Secretary John Kelly.