Around 40 volunteers from Hampshire Search and Rescue have joined county police officers in the hunt for Louise Smith, 16 from Leigh Park.
Louise was last seen on Friday, May 8 in Somborne Drive, Leigh Park – and has not been in contact with her family since then.
A man and woman, both 29, were arrested on Friday on suspicion of kidnap. They have since been bailed by police.
A police spokesman said: ‘The investigation team are carrying out [searches] these in locations we know Louise liked to go or regularly visited in and around the area.’
‘Investigations are ongoing and we remain keen to hear from anyone who may be able to help us locate missing Louise.’
Trevor Vidler from Hampshire Search and Rescue described the huge effort to find Louise, with search and rescue teams from the Isle of Wight and Sussex also called upon for help.
He said: ‘Currently we are searching for a missing 16-year-old girl in the Havant Thicket area.
‘On Sunday, there were 16 police officers and around 40 volunteers on site – it’s a massive operation.
‘Everybody is determined to find Louise as soon as possible.’
On Friday night, Chief Inspector Alex Reading said: ‘Our priority is to find Louise and make sure she is safe.
‘We have been working hard since Louise was reported missing to locate her and so far we have received great support from the community, for which we are very thankful.’
Search and rescue teams are deployed on missing person cases by the police force, following authorisation from the police search adviser.
Louise is white, about 5ft 2in and slim with straight, black, shoulder-length hair.
She was last seen wearing black jeans, a black and white striped T-shirt, black trainers and a black coat with a fur hood.
Anyone who has information on Louise’s location is asked to call 101, quoting the police reference number 44200163113.