Malaysian police have uncovered more than 500 mortar shells, believed to be of World War II vintage, a report said Sunday.

The shells, measuring between 60 millimetres (2.4 inches) 150 millimetres (six inches) in diameter were recovered in southern Malaysia's Johor state after five youths found seven of the shells while fishing along the Gatom river, the Star said.

District police chief Mohamad Hazam Abdul Halim said some villagers saw the youths playing with the shells they had brought back to the village.

Left behind by British

The police then cordoned off the area, while bomb disposal experts searched the area, he said.

"The team managed to uncover 545 shells and we believe they could still be active," Mohamad Hazam was quoted as saying by the Star.

"We also believe the shells were left there by the British Army during the Second World War," he said.

Police were searching the area for more shells, he said. The bomb disposal unit plans to set off the shells at a police firing range Monday. - AFP