Zamboanga City (Philippines), Sep 6 (DPA) Four people drowned Sunday when a passenger ferry with 964 people aboard sank in the southern Philippines, leaving about 90 missing, officials said.

The Superferry 9 sank hours after it tilted to the right by 40 degrees off Siocon town in Zamboanga del Norte province, 810 km south of Manila, navy spokesman Lieutenant Colonel Edgard Arevalo said.

'Four people are already dead,' he said.

Defence Secretary Gilbert Teodoro said the dead included a man and a child who drowned as some passengers jumped into the water in panic.

Teodoro said 'less than 100, about 90 or so' of the 847 passengers and 117 crew were unaccounted for.

He said the navy, coast guard and air force were all helping search for the missing people. He added that Aboitiz Transport Systems Corp, owner of the Superferry 9, was also cooperating with the authorities.

The ferry issued a distress signal before dawn Sunday as it listed dangerously in the waters off Siocon. It left the southern city of General Santos Saturday en route to the central city of Iloilo when the accident happened.

Jess Supan, Aboitiz vice president for safety and security, said the boat's captain had ordered passengers and crew to abandon ship two hours after the ship started to list.