Two dead, two critics after the Sydney dance music festival

Two people have died in suspected drug overdoses after the Defcon.1 music festival.

Two people have died and two others are seriously ill in the hospital after multiple suspicions of overdose at the music festival of Sídq Defqon.1.

A man, 23, and a woman, 21, collapsed at the Castlereagh festival around 9 pm on Saturday and died shortly thereafter at the nearby Nepean hospital, police said Sunday.

A woman from Jamisontown, 26, remains in critical condition at the Nepean hospital, while a man from Artarmon, 19, flew to Westmead Hospital and is in intensive care.

Police said 13 others came to the hospital for drug-related problems, while about 700 people sought help from medical staff at the festival.

The organizers of Defqon.1 had warned ticket holders that the festival's drug policy was zero tolerance.

"This means that all types of soft and hard drugs are prohibited, if drugs are found, they will be handed over to the police," said a statement on the festival's website.

Police say 10 people were charged with drug offenses, including two 17-year-old girls who allegedly loaded 120 capsules "internally" at the scene.

In total, 69 people were found in possession of drugs at the festival held at the Sydney International Regatta Center.

Local detectives have formed a new police attack force, dubbed Highworth, to investigate the two deaths.

The police will hold a press conference at noon.