SEOUL, South Korea — Officials investigating the mysterious sinking of a South Korean warship in waters disputed by North Korea believe that the ship was hit and torn apart by an “external explosion,” the government announced Friday.

Its first official statement on the cause of the sinking came amid rising official and private speculation over a possible North Korean involvement.

“It was highly likely that it was an external, rather than internal, explosion,” Yoon Duk-yong, head of the government team of military and private investigators, said at a nationally televised news conference.

The news conference came a day after the stern of the ship was lifted out of the water, allowing investigators to look more closely at the damage. Officials also found 36 dead sailors inside, bringing the death toll to 38. Eight sailors remain missing, while 58 were rescued the night the ship sank.