SEOUL (Reuters) - Investigators probing the deadly sinking of a South Korean navy ship in March near the North have concluded that a torpedo was the source of an explosion that destroyed the vessel, a news report said on Friday.

The team of South Korean and foreign investigators found traces of explosives used in torpedoes on several parts of the sunken ship as well as pieces of composite metal used in such weapons, South Korea’s Yonhap news agency said quoting a senior government official.

South Korean officials have not officially accused the North but made little secret of their belief Pyongyang deliberately torpedoed the 1,200-tonne corvette Cheonan in March near their disputed border in retaliation of a naval firefight last year.

The metallic debris and chemical residue appear to be consistent with a type of torpedo made in Germany, indicating the North may have been trying to disguise its involvement by avoiding arms made by allies China and Russia, Yonhap quoted the official as saying.

North Korea has denied involvement and accused South Korean President Lee Myung-bak’s government of trying to use the incident for political gains ahead of local elections in June.