The carcass of another elephant was found in Habarana today, the Wildlife Department said.
An investigation had already been launched into the discovery of four wild elephants found dead in Habarana yesterday.
Wildlife officers said the three elephants were believed to have died under suspicious circumstances.
The carcasses were found near a tank bund in Hiriwadunna, Habarana and among them was a pregnant elephant.
The fifth elephant was found dead today and a search has been launched in the area fearing more elephants may have been poisoned.