More than $100m worth of chemicals used in the manufacturing of illicit drugs were seized in raid, police say.

South African police have uncovered an industrial-scale meth lab and arrested four suspects, including two Mexicans, in one of the country’s biggest-ever drug busts.

The laboratory was discovered on a farm in Groblersdal, a small town in Limpopo province in the northeast of the country, the police said in a statement on Saturday.

Limpopo is the northernmost province of South Africa; it borders Botswana, Zimbabwe and Mozambique.

Law enforcement agents found large quantities of chemicals, such as acetone, used in the manufacturing of illicit drugs, including crystal meth, with an estimated street value of 2 billion rand ($109.5m), the statement said.

“What makes this different from other [seizures] is the involvement of Mexican citizens,” said Katlego Mogale, national spokesperson for the Hawks, an elite police unit that took part in the raid.

“It means that our task has just become very difficult,” she told the Reuters news agency.

It is not clear whether the suspects were manufacturing drugs to distribute within the country or elsewhere, she said.

South Africa is a major drug transit country due to its geography and international trade links and is also a growing market for synthetic drugs, according to the United Nations Office on Drugs and Crime.

Methamphetamine trafficking, in particular, is on the rise in Africa, the UN agency said in its 2023 World Drug Report.

The UN describes methamphetamine as a powerful and highly addictive stimulant that impacts the central nervous system and can cause a rapid or irregular heartbeat.

The United States Drug Enforcement Administration warns that high doses of the substance “may result in death from stroke, heart attack or multiple organ problems caused by overheating”.

Acetone is a colourless liquid used to produce a variety of products, including solvents for paints and plastics, but it can also be also used illegally to produce drugs.

As the investigation continues, the arrested suspects will make their first court appearance on Monday on charges of manufacturing, dealing and possession of illicit drugs, the police statement said.