South Korea's Navy said Tuesday that it had found the body of one of three crew members who were aboard a chopper that crashed into the sea off the country's east coast a day earlier.

At around 6 p.m., the Navy found the body some 1,030 meters under the sea during its search operation that used a remotely operated underwater vehicle.

The body was confirmed to be the Lynx antisubmarine helicopter's main pilot, identified only by his surname Kim. Along with Kim, a secondary pilot and a naval non-commissioned officer were aboard the crashed aircraft.

"Lieutenant Kim's body was found just outside the helicopter, and we are trying now to find the rest of the missing crew," a Navy official said, declining to be named.

The Navy also said it retrieved parts of the helicopter.

The helicopter sent out a distress signal and disappeared from radar eight minutes after it took off from an Aegis destroyer at 8:57 p.m. for a joint military drill between the South Korean and U.S. navies, a spokesman said in a briefing.

"In a nighttime search, the Navy found and recovered parts of the helicopter and the pilot's helmet. The pilot sent four Mayday signals before the chopper crashed," the official said.

The Navy is looking into what caused the accident. 

All 20 Lynx choppers currently operated by the Navy will be suspended to avoid a similar accident, according to the Navy.   

The crash site is estimated to be in waters 1,300 meters deep and 52 kilometers east of Yangyang, Gangwon Province. The site is a "bit away" from the inter-Korean maritime border, the Northern Limit Line (NLL), the official explained. 

Pyongyang does not acknowledge the NLL, saying it was drawn unilaterally by the U.S.-led United Nations Command when the 1950-53 Korean War ended in a cease-fire. 

But the weather conditions during the drill were favorable. For example, wave height, visual range, and wind speed and direction all met the requirements for a drill, he said.  

The chopper was engaged in joint maritime operations, the latest display of the allies' military might in response to North Korea's growing nuclear and missile threats.  

In its latest provocations, the North conducted its fifth and most powerful nuclear test early this month, only four days after firing off three ballistic missiles into the East Sea. 

The crashed helicopter is more than 30 years old and was first deployed by the Navy in 1999. (Yonhap)