Detectives investigating a collision in Westminster are appealing for witnesses and anyone with dash-cam footage to come forward.
Police were called by the London Ambulance Service (LAS) at 18: 43hrs on Tuesday, 2 August to reports of an injured motorcyclist on Harrow Road, W9.
Officers attended. The 25-year-old male rider of the motorcycle was taken by LAS to a Central London hospital where his condition remains critical.
His next of kin have been contacted.
Police enquiries have established that the motorcyclist was in collision with a Mini Cooper and detectives are very keen to hear from anyone who has dash-cam footage, or who witnessed the collision but has not yet spoken with police.
Anyone with information should call the incident witness line direct on 0208 543 5157, dial 101 or Tweet @MetCC quoting 6308/2AUG.
To remain 100% anonymous call the independent charity Crimestoppers on 0800 555 111 or visit Crimestoppers-uk.org.