Seoul, May 6 (DPA) Investigators have concluded that North Korea was probably involved in the mysterious sinking of a South Korean warship in March, a news report said Thursday.

An examination of the wreck of the Cheonan found traces of explosives from a torpedo, the Dong-A-Ilbo newspaper reported, citing a member of the investigation team.

The defence ministry in Seoul denied the report, saying that its investigations have not been concluded.

According to the Dong-A-Ilbo, investigators also found pieces of a type of aluminium not used in South Korea that are believed to be from a torpedo. Therefore, only one other country could have attacked the 1,200-tonne ship, an investigator was quoted as saying.

The results of the investigation are to be released by mid-May, the report said.

The Cheonan went down March 26 near the disputed border with North Korea in the Yellow Sea after witnesses heard an explosion and the ship broke apart. Forty-six sailors died in the disaster.

First examinations of the wreckage in April indicated the ship may have sunk after being hit by a torpedo or sea mine.

North Korea rejected any responsibility for the sinking amid growing speculation over its involvement. Seoul so far has shied a way from directly accusing the Stalinist state.