The origin of aluminum fragments taken from the site where a warship sank cannot be determined at present, a senior government official said Saturday, toning down speculation that the metal may have come from a torpedo, Yonhap news agency said Saturday.
The official, whose name was withheld, told the news agency that one of the four small aluminum pieces and one piece of plastic material may have come from the 1,200-ton corvette that broke in two and sank on March 26.
"At present, it is too early to say if the pieces were from a torpedo or other type of explosive device," he said.
The official said the ill-fated warship's hull was made of steel, but its superstructure above deck was made from lighter aluminum. Such building techniques to reduce warships' top-heaviness, which can hurt stability, are common.
On Friday, Minister of Defense Kim Tae-young said the military collected some pieces of aluminum from the site where the Navy ship Cheonan sank on March 26, that were believed not to be from the wreckage of the sunken vessel.
"We found the aluminum was a little different from the type we use," Kim said at a National Assembly committee session.
Investigators have pointed to a North Korean torpedo attack as the likely cause of the sinking of the 1,200-ton Cheonan near the disputed western sea border with North Korea. Aluminum is a key element used in making torpedoes, according to an expert.