SA police said the above pills might be ‘related’ to the death. (Supplied)

A man has died and another is in a critical condition from suspected drug overdoses at Stereosonic music festival in Adelaide.

Police said the man received medical attention at the festival from paramedics around 5pm, but later died in Royal Adelaide Hospital.

Police said he was in possession of a number of pills and they believe he had taken an illicit substance.

Almost 11,000 people were at the Adelaide festival by 3pm. (9NEWS)

The second man fell ill around midday and was taken to hospital after a “medical episode”, where he remains in a critical condition.

The electronic music festival was taking place at Bonython Park in the West Parklands of the city.

The man’s death comes exactly one week after 25-year-old Oyster Bay pharmacist Sylvia Choi died after taking drugs at the music festival’s Sydney show.

A short time ago, festival organisers posted a statement on their Facebook page imploring people to “see the dangers”.