The Philippine defense department said Monday that the death toll from a military plane crash in the country's south the day before has risen to 52, 49 of them among those on board and three of them civilians killed on the ground.

The department also said 47 military personnel and four civilians were injured. All 96 people on board the plane, mostly army personnel who were being ferried for deployment to the restive south, have now been accounted for.

Philippine national flag. (Pacific Press/LightRocket/Getty/Kyodo)

An investigation has started into the crash of the Philippine Air Force C-130 transport plane on Jolo Island in Sulu Province, the department added. A senior military official said the plane may have failed to regain thrust and crashed after missing a runway while trying to land.

Armed Forces of the Philippines spokesman Edgard Arevalo told reporters that most of those on the plane were personnel who had newly graduated from a military training school.

While there is speculation about the cause including weather conditions, overloading and an attack by the Abu Sayyaf Islamic militant group, Arevalo rejected them for now.

"We have to wait on the result of the investigation," Arevalo said, adding the plane was not overloaded and the pilots were experienced.

The plane crashed and burst into flames several kilometers from the airport in Jolo as it was preparing to land, local media reported. The aircraft was carrying army personnel from the capital Manila to Jolo via Mindanao Island in the south.

The aircraft had been delivered by the United States earlier this year under a military aid program.

The U.S. national security adviser, Jake Sullivan, expressed condolences in a statement Sunday and said the United States stands shoulder-to-shoulder with the Philippines and ready to provide appropriate support.

Jolo is one of the areas in the country's predominantly Muslim south where the Abu Sayyaf group operates. The group is linked to kidnappings and bombings in the region.


Related coverage:

45 killed in Philippine military plane crash