Footage of a woman taken outside a nightclub in Hull is believed to show some of the last images of missing student Libby Squire before she disappeared.
The CCTV footage, obtained by The Press Association, shows a woman dressed in black walking along the road near to The Welly club, on Beverley Road, in the city.
Humberside Police said they believe the woman in the video is the University of Hull student, filmed on the evening of January 31, shortly before she was reported missing.
The footage was released on the 12th day of the search, as police revealed that 50 detectives and hundreds of uniformed officers had been working around the clock to try to find Miss Squire.
The CCTV was filmed by a camera on a lettings agency next door to the club and shows Miss Squire, who appears to be dressed in a black jacket and short black skirt, stumble near barriers on the road as she walks towards the nightclub.
A police spokeswoman said the force was aware of the footage and said: "We do believe it is her."
The spokeswoman said she could not confirm that footage taken a few minutes later was Miss Squire.
Around two minutes after the first sighting of the student, a woman wearing a similar outfit is seen walking away from the area of the club and standing in the road near a vehicle.
Lukasz Rybus, owner of Lucas Properties where the CCTV cameras are located, said the footage was filmed at around 11.20pm on January 31.
The 21-year-old is believed to have taken a taxi from the nightclub after she was refused entry.
Police said she was dropped off near her home at around 11.29pm and was then seen near a bench on Beverley Road around 10 minutes later.
More CCTV footage, released last week after it was obtained by ITV News, showed a man getting in and out of a car, minutes after the last sighting of the philosophy student.
In the video, the unidentified man is seen opening the front passenger door before getting back into the car and driving away at around 12.09am on February 1.
Miss Squire was reported missing that day and an intensive search has been conducted by police since that time.
On Tuesday, a force spokesman said: "It's been 12 days since Libby Squire, 21, went missing in Hull.
"Since that time, we have had hundreds of uniformed officers and approximately 50 detectives who have been working around the clock to try and find her."
He continued: "We aren't stopping our searches for her and continue to appeal to the public for your assistance and thank everyone so far for your help."
The investigation has seen specialist search teams, underwater officers, dog teams, neighbouring forces, search and rescue teams, fire officers, the coastguard, the police helicopter, local businesses and members of the public taking part in the search.
Officers have repeatedly scoured gardens, alleyways, waterways and a pond in an area around Miss Squire's home on Wellesley Avenue.
Large digital posters displaying the face of the missing student have also been placed around Hull city centre and at petrol stations, while local businesses have put up posters on their premises.
On Wednesday, Pavel Relowicz, of Raglan Street, Hull, was arrested on suspicion of abduction in connection with Miss Squire's disappearance.
On Sunday night, he was charged with three unrelated offences and appeared at Hull Magistrates' Court on Monday morning.
Relowicz pleaded not guilty to charges of voyeurism, outraging public decency and burglary.
The court heard that he is accused of masturbating in the street where Miss Squire lives; watching another person "doing a private act" for his own sexual gratification; and stealing vibrators, sex toys, knickers, condoms, photographs and computer equipment from three people's homes.
Police said the 24-year-old "remains under investigation" in connection with Miss Squire's disappearance and said letters have been posted through doors of houses around the Raglan Street area, asking residents if they saw anything on the night the student went missing.