An official said the onset of the southwest monsoon had led to flooding in the elephant habitat in Dimbulagala, around 250 kilometres (155 miles) northeast of the capital Colombo.

"We were alerted by villagers to three young elephants who had drowned last evening, but when we went to the marshy area we found four more," a regional wildlife official said.

He said autopsies will be carried out on the seven carcasses on Monday, but a preliminary investigation suggested that the animals had gotten bogged down in the marsh and drowned.

In 2019, seven elephants were similarly found dead in the north-central region of the country. A year earlier in 2018, another seven drowned closer to the area where the latest deaths were reported.

Sri Lanka's wild elephant population has dwindled to just over 7,000, according to the latest official data, down from an estimated 12,000 at the beginning of the last century.