CAIRO, - At least nine people drowned when their boat sank on a family excursion on a lake just south of the Egyptian coastal city of Alexandria, the governor's office said on Tuesday.

Seven people survived the accident on Lake Mariout including five who required medical treatment, a statement said. A search was under way for an unspecified number of missing people.

The cause of the accident was unclear.

The boat sank after sunset on Monday, medical and security sources said.

(Reporting by Ahmed Salem and Ahmed Mohamed Hassan Writing by Aidan Lewis; Editing by Nick Macfie) ((Aidan.Lewis@tr.com; +20-1001174410;))