The cause of death of 21 young people at Enyobeni tavern last month is still yet to be determined

The interior of Enyobeni tavern where the teenagers died on 26 June. Photograph: Siphiwe Sibeko/Reuters

Investigators have found traces of the toxic chemical methanol in the bodies of 21 teenagers who died in a nightclub in South Africa last month.

The tragedy at the Enyobeni tavern in the poor Scenery Park township in the coastal city of East London on 26 June caused shock and grief in a nation used to seeing casualties from a widespread culture of heavy drinking.

The announcement on Tuesday that methanol had been discovered came amid rising anger at the failure of authorities to pinpoint the cause of death.

“Methanol has been detected in all the 21 individuals that were there, however, there is still the progressive analysis of the quantitative levels of methanol and whether it could have been the final cause of death,” Dr Litha Matiwane, the Eastern Cape provincial deputy director for clinical service, said at a press conference in East London.

Methanol is a toxic form of alcohol that is used industrially as a solvent, pesticide, or alternative source of fuel. It is not used in the production of alcohol sold for human consumption.

“The first way it gets into the body is to ingest it. But it is a byproduct of other chemicals, so it could have been something else. Hence we say we are investigating,” Matiwane said.

Alcohol poisoning and inhalation of carbon monoxide have been ruled out as possible causes of death although traces of both were detected in the bodies of all 21 victims.

Many of the teenagers were found dead in the tavern, their bodies strewn across tables and couches, while others died after they were rushed to nearby health facilities.

A regional newspaper, DispatchLive, said shortly after the tragedy that its reporters had seen bodies “lying bizarrely, as if they collapsed to the floor suddenly while dancing or in the middle of a conversation, some seemingly in the social circles they were engaging with,” and other bodies “slumped across chairs and lying over tables”.

Unverified pictures shared on social media showed bodies with no visible signs of injuries lying on the floor of the club.

South Africa’s police will be guided by the final results of the toxicology analysis to determine whether anyone will face criminal charges for the 21 deaths, the national police minister, Bheki Cele, has said.

Cele has described victims collapsing from about 2 am on 26 June. “They died as they danced. They danced and fell and died, literally. And they were pushed to the side and others kept dancing. Others felt dizzy and fell asleep on the sofa and died,” the minister said shortly after the incident.

The 52-year-old owner of Enyobeni tavern and some employees are currently out on bail as they face charges related to the violation of liquor trading laws, including the sale of alcohol to children.

Angry mourners of some victims have complained that weeks of calls to shut down the tavern went unheeded.

The South African president, Cyril Ramaphosa, spoke at a mass funeral for the teenagers and vowed that his government would take action to prevent alcohol from being served to people under the legal drinking age of 18.

Many venues in urban and rural areas of South Africa often flout licensing laws. Overstretched police forces and local government officials often turn a blind eye to such law-breaking, sometimes in return for bribes.

Police are looking for suspected gang members who killed 15 people in a tavern near Johannesburg, the country’s commercial capital, using an assault rifle and 9mm pistols earlier this month.

The attack in the Nomzamo township in Soweto came amid a spate of gun violence. At least seven people were shot dead in similar attacks elsewhere in South Africa over the weekend.

Campaigners have called for a crackdown on increasingly powerful organized criminals armed with military-grade weapons. Others have called for more intensive policing of pubs and bars.