A 23-year-old man who died from a suspected drug overdose at Defqon. 1 over the weekend posted information about police sniffer dogs at the popular music festival just weeks before the event.

Joseph Pham, from Edensor Park, was one of four revellers who collapsed at the music festival in Penrith, in Sydney's west, on Saturday night, according to The Daily Telegraph.

Emergency services were called to the festival after Mr Pham and a woman, 21, collapsed at 9pm.

Joseph Pham (pictured), from Edensor Park, was one of four revellers who collapsed at Defqon. 1 music festival in Penrith, in Sydney's west, on Saturday night

The pair were both taken to Nepean Hospital where they died a short time later.

Two other revellers, including a 19-year-old man and 26-year-old woman, are in a serious condition in hospital.

Mr Pham posted about the festival on his social media in the lead up to the event.

He shared a post from 'Sniff Off', a group that advocates for no more sniffer dogs, drug legalisation and pill testing, three weeks before his death.

The post discussed the possibility of New South Wales Police forbidding people caught with drugs entry to the venue.

Sniff Off wrote: 'It's ridiculous that going to a music festival in Sydney requires this much anxiety and guesswork, but rest assured that Sniff Off is doing as much we can to look out for your rights.'

However, Mr Pham was excited for the world-renowned festival.

On August 15 he posted on social media: 'There's only a month left until Defqon. 1 Australia!

'Hope to see you there!'

Over 700 people at the event sought assistance from medical professionals, while police recorded dozens of drug-related arrests and seizures.

Two people are dead and another two remain in hospital fighting for their life after suspected drug overdoses at a notorious electronic music festival

Police said an additional 13 people attended Nepean Hospital for drug-related issues during and after the festival.

Officers conducted 355 drug searches throughout the day. Of this, a staggering 69 people were allegedly found to be in possession of drugs, and 10 were charged with drug supply offences.

A 22-year-old man from Bankstown was allegedly found with 20 packets of the drug GHB and was charged with attempting to supply an illegal drug.

People affected by drugs at the venue were rushed to nearby Nepean Hospital, where one woman remains in a critical condition

Two other men, aged 33 and 27, were charged with supplying MDMA.

Another two teenager girls, aged 17, were charged with supplying after they were allegedly caught carrying 120 capsules internally.

Two more men and three more women were charged with offences relating to MDMA, cocaine and ecstasy.

Police presence was strong throughout the day, with police calling their approach a 'multi-faceted operation', involving the Nepean PAC, Police Transport Command, Enforcement Squad and the Police Dog Unit.

Defqon Australia organisers released a statement to news.com.au in relation to the deaths.

Police have formed Strike Force Highworth to investigate the deaths of a 23-year-old man and a 21-year-old woman, who died after collapsing at the Defqon music festival

'The organisers of Defqon.1 Australia are deeply saddened by the tragic passing of two of their patrons at Nepean Hospital after attending the festival last night and would like to convey their sincerest condolences to their families and friends.'

'Thoughts and prayers are also with the young man and woman who are still in a critical condition. We are disappointed at the number of reported drug related incidents, we have a zero-tolerance policy in relation to drug use at the festival.'

'Festival organisers are working closely and cooperating with the authorities regarding the fatalities and the number of medical presentations made during the evening, a full investigation is currently underway. As this is a matter with the NSW Police and the coroner and out of respect for the families and friends we are not going to speculate on the cause of death and we will not be making any further statements or comments,' the statement read.

Defqon is an annual music festival held in the Netherlands and Australia which typically plays hardstyle related genres such as hardcore techno, hard house and hard trance

Gladys Berejiklian described the deaths as tragic, and confessed she never wanted the international event to return to Australian shores.

'I never want to see this event held in Sydney or New South Wales ever again — we will do everything we can to shut this down,' ABC reported.

The Sydney International Regatta Centre, which has been the site for the Australian dance party since 2010, announced on Sunday it would no longer host Defqon. 1.

Two other Australians have died at the festival in the last five years, including James Munro who died from a suspected ecstasy overdose in 2013.

An investigation is currently ongoing into the circumstances surrounding the two deaths.

Police urge anybody with information to come forward and contact Crime Stoppers on 1800 333 000.