The US Transportation Security Administration will not allow mobile phones or other electronic devices on US-bound planes at some overseas airports if the devices are not charged.

The new measure is part of the TSA’s effort announced last week to boost security amid concerns that Yemen-based al-Qaeda in the Arabian Peninsula (AQAP) and the Islamist Nusra Front, al Qaeda’s affiliate in Syria, are plotting to blow up an airliner, US officials said.

As part of the increased scrutiny at certain airports, security agents may ask travellers to turn on their electronic devices at checkpoints and if they do not have power, the devices will not be allowed on planes, the TSA said.

A US source familiar with the matter said laptop computers are among the devices security screeners may require passengers to turn on.U.S. officials are concerned that a cellphone, tablet, laptop or other electronic device could be used as a bomb.

US officials singled out smartphones including iPhones made by Apple and Galaxy phones made by Samsung for extra security checks on U.S.-bound direct flights from Europe, the Middle East and Africa.

AQAP has a track record of plotting such attacks.

Its innovative bombmaker, Ibrahim al-Asiri, built an underwear bomb used in a failed 2009 effort to bring down a Detroit-bound airliner, and his devices were implicated in other plots.

There was no immediate indication US intelligence had detected a specific plot or timeframe for any attack.

US officials say the United States has acquired evidence that Nusra and AQAP operatives have tested new bomb designs in Syria, where Nusra is one of the main Islamist groups fighting to overthrow President Bashar al-Assad.

The TSA also called for closer checks on travellers’ shoes.