The partially-clothed body of a four-year-old girl was found in a farm dam in Wellington on Tuesday morning, Western Cape police said.

A relative found Abranesia Pass's body 400 metres from her home on the De Krome Fountain farm around 7am, said Senior Superintendent Billy Jones in a statement.

"Preliminary investigation by the pathologist on the scene indicates that she died as a result of suffocation. Blood was also found on her mouth and lower body."

She was last seen just outside her family's house around 6.45pm on Monday and was reported missing to police about two hours later.

A post mortem would be conducted to confirm the cause of death.

Police were investigating a case of rape and murder. A man in his late twenties was taken in for questioning on Monday night while the search for the girl was still underway.