Police hunting the killer of landscape architect Joanna Yeates today appealed for information about a 4x4 vehicle seen near to the area where her body was found.

Senior Investigating Officer Phil Jones of Avon and Somerset Police said the light-coloured vehicle was spotted around the time 25-year-old is believed to have disappeared.

He explained: ''We have had a number of reports of vehicles in Longwood Lane during the late Friday evening and early hours of Saturday morning, including a possibly light-coloured 4x4 vehicle.

''This 4x4 and the other vehicles may be completely unconnected but I urge anyone in that car or any other driver in the vicinity that night to come forward.''

Detective Chief Inspector Jones said: ''The team and I have been working tirelessly to analyse information from potential witnesses and the public.

''I understand that both the public and the media have many questions. As I'm sure you'll appreciate, some of these questions could prove vital when it comes to an arrest or prosecution, therefore I have to be somewhat guarded on what I am able to say.

''We are carrying out painstaking, detailed forensic analysis of her flat and the outcomes from this could take a considerable length of time, despite prioritising and working closely with all our forensic service providers.

''I am satisfied that Jo got back to her flat but I'm not able to speculate whether she let somebody into the flat, whether somebody was already in there or whether someone broke into the flat.

''At this time I cannot say where or when Jo was killed, or when her body was left on Longwood Lane.

''The significant snowfall in the early hours of Saturday December 18 has a considerable impact on this and I am working with numerous forensic specialists to determine the timings.''