A South African mother has appeared in court charged with trying to sell her 19-month-old baby on the internet for 5,000 rand ($A518.52).

Police were tipped off that the woman, 20, had offered her son for sale on the popular advertising website Gumtree.

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“We met her and there was an exchange of money with an undercover police officer,” Hangwani Mulaudzi, spokesman for the Hawks special crimes investigation unit, said.

“She gave us the money and we arrested her directly.”

The woman appeared in court in Pietermaritzburg, KwaZulu-Natal province, on human trafficking charges, and her case was adjourned until October 26.

“Gumtree South Africa’s customer service team was alerted that a young woman had placed an ad on the site advertising a child for sale,” company spokeswoman Claire Cobbledick said in a statement.

“The team immediately removed the ad and blocked the user’s account. (We) escalated the issue to the corporate office that engages law enforcement on suspected criminal cases.”

The child was in good health and has been taken into care by social workers.