The mystery surrounding the disappearance of Bradford storeman Michael Allison deepened today.

The 33-year-old went missing after a Christmas party at the Noble Comb pub, Shipley, six weeks ago.

He never made it home to St Paul's Road, Manningham, and a series of land, air and underwater searches have failed to throw up any clues as to his whereabouts.

Now a taxi driver has contacted police to say he took a passenger fitting Mr Allison's description to Frizinghall on the night of his disappearance.

The previous last reported sighting of Mr Allison was by work colleagues at Pace Micro Technology, who saw him in the pub at 8.30pm.

The taxi driver picked up his passenger at the same pub, dropping him off at about 9pm close to Norwood Road, Frizinghall - a mile and a quarter from St Paul's Road.

Detective Chief Inspector Phil Sedgwick, of Toller Lane Police, said: "This new information increases our concern for Michael's welfare and deepens the mystery surrounding his disappearance.

"It seems odd that if Michael was the man in the taxi - and the descriptions, location and timing certainly fit - he has been dropped off between the pub and his home."

Officers from Toller Lane Police carried out house to house inquiries in the Norwood Road area yesterday.

DCI Sedgwick said although no leads had yet emerged they would be making follow-up calls this week.

He added: "It's increased awareness in that area because, even after all the publicity there's been, there were still people who weren't aware of this.''

More than 100 posters appealing for information have been put up around Shipley, Frizinghall and Manningham.

Officers from British Transport Police and divers from the West Yorkshire Police Underwater Unit have searched railway embankments. And officers from Toller Lane have searched outbuildings and derelict garages.

DCI Sedgwick said: "We are also considering the possibility of a leaflet drop in the area."

Mr Allison, who lives alone, was due to spend Christmas with his sister and her family in Southport. He phoned his sister on the morning of his disappearance to say he had bought the travel tickets - but never arrived.

Mr Allison's sister Pat Cockburn, 43, said their father Joseph Allison, 75, was worried sick about his son. She said: "He's got a heart condition so I've had to keep a lot of the details about what's been happening back from him.''

She added: "The last six weeks have just been awful - one day you think you're coping and the next it hits you twice as hard.

"We just don't know what's happened but it doesn't look too good. I know he wouldn't have not come or got in touch, unless it was something really bad, because we are so close.

"You've got to hold on to the hope that he's okay but deep down you know something's happened but don't want to say it in case it comes true.

"Even his friends over here have been making a few inquiries but nobody's heard anything. The police are in touch virtually every other day and if anyone does know anything we'd ask them to please come forward because someone, somewhere must have seen or heard something - it's the not knowing what's happened which just makes you full of anxiety all the time.''