The body of a missing nine-year-old boy was found in a stream in Eldorado Park on Monday morning, Johannesburg emergency services said.

"The body was found just 150m from where the boy had played," said spokesperson Nana Radebe.

"We want to send out a strong message that streams are not designated areas for swimming. There is a swimming pool nearby."

The boy went missing on Sunday while playing with a friend near the Klipspruit river crossing in Eldorado Park's Extension 9 on Sunday around 6pm.

"His friend said he saw him being washed away," said Radebe.

Emergency services searched for the boy until 11.45pm on Sunday and resumed their search on Monday morning.