KUWAIT CITY — The Gulf nation of Kuwait has warned citizens traveling to the U.S. to check their phones and laptops to ensure they do not contain any material that could be linked to extremist groups.

The official Kuwait News Agency reported Saturday that the Kuwaiti Embassy to Washington also urged citizens to “cooperate fully” with American airport officials seeking access to their devices.

It warns that immigration officials could interrogate Kuwaitis and cancel entry visas if extremist photos, videos or other materials are found.

The warning comes after Kuwaiti media reported that three Kuwaitis were refused entry to the U.S. earlier this year.

Kuwait is a U.S. ally that hosts American troops taking part in operations against the Islamic State militant group.