SEOUL (AFP) - South Korean police said on Tuesday that they were investigating three Samsung managers for possible negligent homicide after a deadly toxic chemical leak at a chipmaking plant last month.

One repair worker died after trying to stop the leak of diluted hydrofluoric acid at the Samsung Electronics' plant in the city of Hwaseong, 43km south-west of central Seoul, on Jan 27.

Four other workers were treated in hospital but later released.

A post-mortem showed the worker had died of exposure to gas given off by the leak, which can damage lungs and bones, and affect the nervous system.

Police said the leak was due to deterioration of rubber seals on the gas container valves and corroded bolts, and the three managers could face charges of negligent homicide.

"Investigations are still underway on how much gas was released ... and its impact on the environment," the provincial police agency said in a statement.

Samsung is the world's top maker of smartphones, memory chips and flat-panel TVs.