Chilean authorities have said they are investigating what killed some 1,300 seabirds that mysteriously turned up dead on a beach.

The birds, which belong to the Procellariidae family, may have drowned after getting trapped in fishing nets or died from a disease such as bird flu, which is not endemic to Chile, said a spokesperson from the country's Agriculture and Livestock Service (SAG).

They were found Sunday afternoon by visitors to a small black-sand beach in the southern town of Lenga, a cove with several hundred inhabitants who live mainly on fishing and tourism.

SAG said it was analysing samples taken from the birds to try to determine the cause of death.

The birds may have drowned after getting trapped in fishing nets or died from a disease. (AFP) (AFP)