Three Chinese villagers got an unexpected surprise when they went looking for scrap metal -- more than 3,500 old Japanese ammunition shells buried during World War Two, Xinhua News Agency said on Tuesday.

The three, from the north-eastern province of Jilin, found the shells with a recently bought metal detector at the site of an old Japanese military airport, the report said.

"Because one of the three understood how to defuse shells, after talking about it between themselves they decided to prepare to defuse it themselves and then sell the cases as scrap metal," the report said.

"Their behaviour caught the attention of nearby villagers who reported them to the police," it added.

The shells were then taken away to be disposed of properly, Xinhua said.