Two people have been arrested in connection with the disappearance of 16-year-old Becky Watts.
Avon and Somerset Police Detective Superintendent Liz Tunks, who is leading the investigation, said: "Whilst the two people are being questioned our search for Becky continues unabated.
"I would like to appeal once again for anyone who might have information about her whereabouts, or anything else that might help us to find her, to call us."
Missing teenager Rebecca Watts
It has been more than a week since the teenager, known as Becky, was last seen at her house in Crown Hill in the St George area of Bristol.
She left home on February 19 with her phone, laptop and tablet computer but did not inform friends or family where she was going, or take extra clothes.
Avon and Somerset Police have been searching for the teenager, described as shy, since she was reported missing by her family at 4pm on February 20.
A discarded laptop found in university grounds next to a park near Oldbury Court Estate in Bristol
Becky's father and step-mum Darren and Angie-Mae Galsworthy said: "We continue to hope that she will be found safe and unharmed but we will prepare ourselves for the worst."
In a statement, the couple said: "We would like to take this opportunity to thank everyone who has assisted in the search for Becky and for the messages of support.
"We continue to work with the police to bring their investigation to a successful conclusion and we would like to ask members of the public to continue to report anything, however small, if they think it may help to find Becky."
Police divers have been carrying out open water searches on the lake in St George's Park, which is close to Becky's home, while police from neighbouring force areas have also been drafted in to help.
An online campaign for the social media savvy teenager was launched by police earlier this week, using the hashtag #FindBecky.
More than 100 people gathered in the Fishponds area of Bristol in an attempt to shine a light on the teenager's mysterious disappearance.
Members of the search party recovered part of a grey Toshiba laptop from woodland while scouring areas near where Becky was last seen. It has since been handed to investigators.
Becky is described as 5ft 4in and slim, with long, bright red hair and was wearing a dark navy blue Puffa jacket with fabric sleeves.
Anyone with information is asked to contact Avon and Somerset Police on 101, or Crimestoppers on 0800 555 111.