A drone strike that sparked fires on two gas vessels in Egypt's Mediterranean port of Damietta has raised a new threat to shipping through the Suez Canal, one of the last major export routes available to Saudi oil amid the expanding US-Iran war.

No one has claimed responsibility for what Egypt's cabinet said on Thursday was an unidentified drone that caused a fire on two vessels at Damietta a day earlier. The port lies near the Suez Canal, which links the Mediterranean and Red Seas.

The drone hit the US-owned gas storage tanker Energos Winter, causing a fire that spread to a second vessel, people familiar with the incident said.

Iran has denied any involvement in the Damietta strike.