POLICE are growing increasingly concerned for missing Daniel Entwistle who was last seen four days ago.

The major search for the little boy in Great Yarmouth, Norfolk, is continuing today but police have admitted that they have so far failed to come up with any significant leads.

Daniel's parents, David, 41, and Paula, 31, have appealed to pupils at his school to help them find their son.

The boy, who was brought up in Padiham until the couple moved South three years ago, went missing on Saturday after leaving his home in Great Yarmouth to visit a friend.

His bicycle was found abandoned on a riverside quay near his home but police have said they are keeping an open mind about his disappearance.

Detective Superintendent Julian Gregory said: "I won't pretend that I'm not frustrated that we haven't found him. We are looking at all the options but at the moment we have nothing that steers us in a particular direction. Abduction is a possible line of inquiry simply because we have a seven-year-old boy missing.

"Clearly the longer he's missing the more concerned we become of his safety."

Police had received 300 calls from the public but none of the information had proven significant.

David and Paula spoke at a morning school assembly dedicated to their son yesterday.

Keith Egleton, headteacher of Greenacre First, Middle and Nursery School, said: "The children are quieter this morning than usual, normally they come bustling into the playground. They were a but more subdued and a bit more thoughtful.

"The children are coping well and know they are in a safe environment. I am concerned for my staff, especially the teaching assistants who are members of the community and one of them babysits for Daniel.

"They know him, they know him very well and it has hit them hard. It's a very close community."

At the assembly, the school's chaplain said prayers for Daniel's family and for his safe return and a candle was lit for the children to focus their thoughts on.

Mr Egleton said: "Daniel's parents were at the assembly and they appealed to the children for any possible help and emphasised that they were able to come to us and talk.

"We are working in close liaison with parents and have gained their permission to pass on any information their children give us to the police, although we have to sift through it a little bit. We have had some important information come through this morning which is being looked at by detectives."

Police are also carrying out searches at a pupil referral unit attended part time by Daniel in neighbouring Gorleston in case he has made his way there.

Detectives are also looking at two reported sightings of Daniel at about 8pm on Saturday close to his home on the Barrack estate and are studying security camera footage from another undisclosed location showing a boy believed to be Daniel.

More than 100 officers are taking part in daily searches of the beach area, riverside, town and industrial estates, all within a 5km radius and police divers yesterday searched the river close to where the bike was found, moving their search a few hundred metres up stream.

A police helicopter searched over the town and further afield, while specially trained civil protection volunteers searched the beach. A fire service crew used an hydraulic platform to check for any sign of the boy at a metal scrap yard close to the dockland and industrial area where the bike was found.

Coastguards said their search for Daniel was one of the biggest they had yet carried out.

Police are using national statistics which chart the behaviour of children who go missing as well as studying the list of local sex offenders.