Leon Rose, 29, appealed for anyone holding Shannon to let her return to her family in Dewsbury Moor, West Yorkshire.

There have been no confirmed sightings of the schoolgirl since she left Westmoor Junior School in Dewsbury at 3.10pm on February 19, following a school swimming trip.

A huge police operation and frantic searches by family and friends have so far failed to find a trace of her.

Mr Rose told Sky News about his fears that Shannon was being held captive somewhere.

"Terrible though that thought is, in some ways that gives me a strange sort of hope," he said.

"At least she would still be alive and there would be a chance that she might be released unharmed."

He continued: "I beg anyone who may be holding Shannon - please, please let her go free.

"She is a good girl. Be kind to her and let her return to her family where she belongs."

Mr Rose is separated from Shannon's mother, Karen Matthews, 32, and lives 10 miles away in Kirkburton, Huddersfield, with Shannon's 10-year-old brother, Ian.

Shannon had written on her bedroom wall that she wanted to go and live with her father but police said the message was just part of an array of scribbles that the youngster had daubed on her wall.

Earlier, Mr Rose, who has four children, told The Sun he wakes up at night wondering where his daughter is.

He said: "All I can think about is, where's my little girl?

"I'd give everything I own for her to be found. I feel she is still alive. I have to believe that - anything else would be too much to bear."

Mr Rose told the newspaper he regretted missing out on years of Shannon's life and said the few photos he has of his daughter are his most treasured possessions.

"I can't bear the thought that we don't know where she is," he said.

"Every morning I wake up hoping: 'Could this be the day we find her?'.

"But the pain goes on. I feel so empty when I go to bed knowing she is still out there and we haven't found her."

Yesterday, detectives released a new photograph of Shannon taken at her school in September last year and urged people to try to remember what they were doing on the afternoon of February 19, if they were in the Dewsbury Moor area.

Police said they were investigating "numerous" possible sightings of the schoolgirl, including one by two boys who claimed to have seen the shy schoolgirl sitting on a wall about half-a-mile from her home "crying her eyes out".

The possible sighting was at 3.20pm - about 10 minutes after the last confirmed time Shannon was seen by a teacher at her school.

A West Yorkshire Police spokeswoman said detectives had also interviewed Shannon's best friend Megan Aldridge, who told yesterday how her friend had been unusually quiet on the bus back from swimming and that another girl had been bullying her.