Bird flu suspected as 1,000 birds found dead in three mass mortality events

South Australian authorities have identified three mass bird mortality events involving more than 1,000 crested terns, which are "presumed" to have died from H5N1 bird flu.

Premier Peter Malinauskas told SA Parliament the deaths occurred on remote offshore islands including Troubridge Island off Yorke Peninsula and two small islands off Kangaroo Island known as North Page and South Page.

The deaths were detected on Wednesday.

As of today, South Australia has recorded 177 confirmed H5 bird flu cases.

The SA government is also investigating a suspected case involving a little penguin from Kangaroo Island.

The discoveries of the mass mortalities were made by the state government's surveillance teams and represent a "significant escalation" of bird flu in the state, Mr Malinauskas said.

"The loss of more than 1,000 birds is deeply concerning, and the state government is treating these events with the utmost seriousness," he said.

"Of particular concern, we are also investigating a suspected case involving a little penguin from Kangaroo Island."

The mass mortalities were revealed in a ministerial statement, which the premier read out to parliament's lower house.

He added that no mass mortality had been reported in mammals, and that H5N1 had not been detected in poultry or livestock.