Police in Moscow have launched a hunt for the baby son of a North Korean diplomat, who's been missing since Saturday.

One-hundred-and-fifty police and officials from the Russian emergencies ministry are involved in the operation.The boy, aged two, went missing at a picnic for North Korean embassy staff at a nearby park in Mosfilmovskaya Street.

Police say they cannot rule out the possibility that the child has been kidnapped for ransom, but there's no report of any demand being received.