South African police say they have dismantled a crystal methamphetamine laboratory, with drugs worth $20m (£15m), discovered on a farm in the east of the country.

Five people "from a North American country" have been arrested, while two others "believed to be from West African countries" fled the scene, a statement said.

Police photographs show industrial manufacturing equipment along with weighing scales and lunch boxes filled with the illegal drug.

In a 2022 Global State of Harm Reduction report, South Africa was described as one of the largest crystal meth consumer markets in the world. Its geography and "porous borders" make it an ideal transit point for illicit drugs, the UN says.

In Friday's raid on the farm in Volksrust, 225km (140 miles) south-west of Johannesburg, the police also seized a pellet gun loaded with blanks.

The farm caretaker, who has also been arrested, was found with three live rounds.

The police had been acting on a tip-off with the informant reporting "a strange chemical smell emanating from the premises [of the farm], which raised suspicions of illicit drug manufacturing".

"We applaud the community members who continue to work with police and provide valuable tip-offs. Intelligence-driven operations are ongoing, and we, as police, will stop at nothing in our quest to collapse the illicit drug trade," Mpumalanga acting commissioner Maj-Gen Zeph Mkhwanazi said.

Last year, a similar discovery on a remote farm in another part of the country led to the arrest of two Mexicans and two South Africans.