Police arrested more than 50 undocumented foreigners on Thursday during a roadblock as part of “Operation Okae Moloa” (Where's the Law?) in Fourways, Johannesburg.

Among them was a doctor from Iran, who was arrested for failing to produce his passport.

Phone somebody to come and get the bike and to bring your passport. If you don't have your passport with you, you are an illegal immigrant and will be arrested and detained,” a police officer can be heard telling the doctor in a Twitter video.

Speaking on radio, SAPS Maj-Gen Mbuso Khumalo said Fourways has been identified as a crime hotspot.

“Those who know they do not belong in the country must carry their passports because [when you are stopped] at a roadblock and can’t produce [the documents] we arrest you.

“Home affairs is also around to process them. They must carry passport all the time otherwise we will arrest them for [being] undocumented,” said Khumalo.

Home affairs minister Aaron Motsoaledi last year gave SAPS the green light to spot check foreigners to ascertain whether they were legally in the country.

“Police have the right to stop and ask about documentation. It doesn't have to be production or physical documentation like during apartheid days, meaning you are not forced to carry documents in your pocket everywhere you go.”

Documents are checked against the national population register.