At about 11.50pm on Monday 4th December evening in Somers Road, police in a marked vehicle spotted a white Honda moped with a rider and a pillion passenger.
The rider of the moped failed to stop, continuing along Margate Road, Victoria Road North and Victoria Road South.
The moped was then involved in a collision with a silver BMW 1 series at the junction of Richmond Road and Clarendon Road.
The two teenage boys on the moped, one from Portsmouth and one from Southsea, suffered serious and life-threatening injuries and have been taken to hospital, where they are currently being treated.
No arrests have been made at this stage.
As part of the investigation, officers are appealing for any witnesses to come forward, as well as anyone with CCTV or doorbell camera footage along the route taken by the moped.
Police would also particularly like to speak to anyone with relevant dashcam footage of the collision or the police pursuit.
Police have said;
As is normal practice in these situations, the matter has been referred to the Independent Office for Police Conduct.
Anyone with information should call 101 quoting reference 44230495917 or report online via the police website.
