Police have launched a manhunt after a child reported he was sexually assaulted by an intruder in his bedroom.
There was no evidence of forced entry at the home in Ickenham, north-west London, and the man fled the scene after the boy said he would call police.
The boy's age has not been revealed to protect his identity.
Police were called to the home on The Greenway at 12.20am on Saturday following the reported sexual assault.
The child is being supported by specially trained officers.
The suspect is described as white, of slim build with short hair and a beard.
He was wearing blue jeans and a t-shirt.
No arrests have yet been made.
Detective Constable Claire Field, from the West Area Command Unit’s Safeguarding team, said: “This matter has clearly caused a great deal of anguish to the boy’s family...
"We are appealing for the public’s help to identify a man who was seen running from the area shortly after the assault.
"It is vital that we speak to him to establish why he was in the vicinity.
“Whilst incidents such as this are thankfully very rare, I would encourage people to ensure that their homes are kept secure at all times and to report anyone acting suspiciously.”
Detective Chief Inspector Natalie Norris from the West Area Command Unit, added: “We fully recognise how concerned our community will be after an incident like this.
"For this reason we have patrols in the area and we are working with partners and keeping them informed.
"Together we are doing all we can to support the family and all those affected.
"This is a horrible incident and thankfully rare, but my officers are working incredibly hard to find the person responsible.”
Anyone who recognises the man in the CCTV image, or who was in the area at the time, is asked to call police on 101 or contact them via Twitter @MetCC using the reference CAD 145/23NOV.
To give information anonymously contact Crimestoppers on 0800 555 111 or online at crimestoppers-uk.org.