The plane crashed in a mountainous area near the southeastern city of Pohang just before 2:00 pm (0500 GMT), around six minutes after take-off, according to South Korea's navy.

The maritime patrol aircraft was conducting take-off and landing training when it crashed, the navy said.

"The Navy has located all four bodies of the maritime patrol aircraft crew and is currently recovering them," the navy said in a statement.

Of the four victims, two were officers and two were non-commissioned officers, according to South Korea's Yonhap News Agency.

No civilian casualties have been confirmed.

The cause of the incident is being investigated, the navy said.

Fire authorities have sent some 40 personnel in response, Yonhap said.

South Korea suffered the worst aviation disaster on its soil in December when a Jeju Air Boeing 737-800 crash-landed and exploded in a fireball after slamming into a concrete barrier.