Peter Faulding, a specialist called in by the family who is assisting police with the search, says his team have been unable to locate the 45-year-old.

The mother-of-two went missing near to the village of St Michael's on Wyre, Lancashire, on 27 January, while walking her dog after dropping her daughters off at school.

Detectives say their "main working hypothesis" is that she fell into the river and Superintendent Sally Riley, from Lancashire Police, reiterated at a news conference on Tuesday that this remained the force's belief at this time.

But Ms Bulley's family and friends have previously claimed there is "no evidence whatsoever" behind this.

Officers are searching the River Wyre, with the help of Mr Faulding's company Specialist Group International (SGI), who joined the search for Ms Bulley on Monday.

However his team, equipped with a £55,000 side-scan sonar able to pick up objects underwater, have not been able to find any trace of Ms Bulley.

On Wednesday, he told reporters that he believes it is "unlikely" that she has been swept out to sea and that the case has left him "baffled".

It comes as Ms Bulley's partner visited the place where police believe she fell into the River Wyre.

Paul Ansell spent 10 minutes on Wednesday along the riverbank near the bench where the 45-year-old's phone was found, still connected to a work Teams call.

The lead and harness for Willow, her springer spaniel dog, were found on or close to the bench.

Mr Ansell spoke with Mr Faulding at the scene, and he appeared to take him through aspects of his search, which is now into its third day.

Police divers have also been conducting searches on sections of the river close to the bench.

Mr Ansell was accompanied by a police officer and Emma White, a family friend of Ms Bulley.

Two police dinghies with divers were seen setting off from the riverbank and going upstream to continue the search.

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Earlier this week, in a statement released through Lancashire Police, Mr Ansell said their girls "miss their mummy desperately" and "need her back".

In a voicenote sent to Sky News, Mr Ansell added: "We have to find her safe and well. I can't put those girls to bed again tonight with no answers."

Superintendent Sally Riley, of Lancashire Police, said detectives had looked at "every single" potential suspicion or criminal suggestion that had come in and discounted them.

She spoke after suggestions Ms Bulley's phone could be a "decoy" and about gaps in CCTV coverage of the area from where she vanished.

Police said it was still a "possibility" she left the area by one path not covered by cameras which is crossed by the main road through the village.

Officers were trying to trace dashcam footage from 700 drivers who passed along the road at the time she disappeared, which was around 9.20am.

Detectives have revealed they are looking at 500 active pieces of information but have not found "anything of note" yet.