A drone hit a US-owned gas storage tanker at Egypt’s Mediterranean port of Damietta, British maritime security firm Ambrey said on Wednesday, in an initial assessment that could signal a further spread of conflict across the Middle East.

A statement from Egypt’s petroleum ministry confirmed a fire at the port but made no mention of a drone attack and did not provide a cause for the incident.

Port services firm Inchcape said in a separate message two gas tankers had caught fire at Damietta.

The drone hit floating storage tanker Energos Winter, causing a fire that spread to another vessel, Gaslog Salem, three trading sources familiar with the incident said. Two separate security sources said the likely cause of the blast was assessed as a drone strike.