Police were called to Rowdown Fields in New Addington yesterday morning.
The Met says the remains will be sent away for full analysis.
They are asking that people do not speculate on the circumstances of the discovery.
Superintendent Lewis Collins said: “We are aware of the concerns within the local community following the discovery of possible human remains in the Croydon area this morning.
“The remains will be sent away for full analysis.
“I would like to reassure you that officers remain on scene and we will be carrying out a number of enquiries over the coming days to establish exactly what has happened.
“While our investigation is still at a very early stage, I would ask that people do not speculate on the circumstances and will we update you as soon as we have further information.”