The toxic chemical methanol has been identified as a possible cause of the deaths of 21 teenagers at a bar in the South African city of East London last month.

Methanol was found in all their bodies and investigations are continuing to determine whether the levels of the toxic chemical were enough to have killed them.

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

Authorities are still awaiting the conclusive results of tests, which are being conducted at a laboratory in Cape Town, he said.

The interior of the Enyobeni Tavern in Scenery Park where 21 teenagers lost their lives almost two weeks ago. Photo / AP

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

It is yet not known how the youngsters ingested the methanol.

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, said Matiwane.

The teenagers died at the Enyobeni tavern in East London's Scenery Park townshipearly on June 26, shocking the country and resulting in several investigations by the police and liquor license authorities.

Many of the teens, ranging in age between 13 and 17, were found dead in the tavern, with their bodies strewn across tables and couches. Others died after they were rushed to nearby health facilities.

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, Police Minister Bheki Cele has said.

The owner of Enyobeni tavern and some employees were arrested and are on bail as they face charges related to the violation of liquor trading laws, including the sale of liquor to children.

South African President Cyril Ramaphosa spoke at a mass funeral for the teens and vowed his government would take action to prevent alcohol from being served to children under the legal drinking age of 18.

The deaths of the young people are separate from shootings at three bars in South Africa this month in which a total of 22 people were killed.

In all three massacres, the suspects opened fire on patrons before speeding off in their vehicles. Notably, the attackers did not rob the victims.

In the worst shooting, gunmen burst into a bar in Johannesburg's Soweto township and opened fire, killing 16 people.
- AP