The incident happened at approximately 14:30hrs on Thursday, 7 January at Northala Fields, Northolt.
The victim, a five-year-old boy, was approached by a man who picked him up and ran a short distance with the boy before being confronted by the child’s mother. The boy was then put down – he was unharmed.
The suspect has been described as having a pale complexion, of slim but muscular build, possibly with a moustache and was wearing blue/green hooded top, with a small white logo across the front, blue jeans with rips on the front and black trainers.
Detective Constable Ashleigh Nelson from West Area Command Area CID said: “Incidents of this nature are very rare but I understand the concern it may have caused in the local community. I want to reassure people we are doing everything we can to find out who is responsible.
“I would appeal to anyone who has mobile phone or dashcam footage of the suspect, which may assist with identifying him, to get in contact as soon as possible.”
Anyone with information should call police on 101 or tweet @MetCC quoting CRIS 2500522/21.