A website allowing victims of street crime to formally report and map where in the capital they were robbed or assaulted was launched today.
Streetviolence.org provides a Google map of London on which users can plot exactly where they were targeted by criminals and give a description of the incident.
It is hoped the independent initiative, launched by charity Witness Confident, will help warn local people about specific crime hotspots, encourage witnesses of crimes to come forward, allow victims to thank Good Samaritans and let users track arrests and prosecutions of law-breakers.
However, Scotland Yard has refused to endorse the site, saying using a website to report crimes could delay investigations.
Witness Confident's director Guy Dehn said the new site "cuts the initial hassle and frustration that puts many victims off reporting the crime to begin with".
He told the BBC: "As a way of telling the police you can help, the site is a welcome alternative to hanging behind at the scene, standing around at a police station or waiting in line at a call centre.
"This matters as there's little chance the police can make our streets safer if witnesses don't come forward,"
Mr Dehn added: "One of the things that has been lost in recent years is engagement with police....If you want to help police, this allows you to contact them 24/7 at the convenience of your computer."
Scotland Yard said it had been liaising with the charity for more than a year after expressing interest in some of its early proposed functions.
But officials reached a decision not to support the launch earlier this month.
"We do not endorse the reporting of street crime through the MPS website or any other third party website," the Met said in a statement.
"This is predominantly due to concerns over victim safety and the importance of deploying officers in person as quickly as possible to this scenes of serious street crime.
It added: "Street crime is taken very seriously by the MPS, and in order to reduce street crime and catch offenders, the MPS urges victims to contact police in the quickest way possible by calling 999 or speaking to an officer on patrol nearby."
The force said it will continue to monitor the website and is open to exploring any initiatives to help reduce crime and catch criminals.
Kit Malthouse, Deputy Mayor for Policing and Crime, said he hoped the website "progresses in its aim to encourage greater on-line reporting and facilitating greater information sharing amongst victims, witnesses and the police".