THE increasingly desperate search for missing seven-year-old Daniel Entwistle has switched to a river near his home.Police used sonar equipment operated from a boat, to search the riverbed from the mouth of the Yare at the North Sea for a two-mile stretch of the water, which can be up to 20ft deep.

THE increasingly desperate search for missing seven-year-old Daniel Entwistle has switched to a river near his home.

Police used sonar equipment operated from a boat, to search the riverbed from the mouth of the Yare at the North Sea for a two-mile stretch of the water, which can be up to 20ft deep.

A bicycle believed to belong to the youngster, who has been missing for more than three days, was found abandoned by a harbour wall on the River Yare in his home town of Great Yarmouth, Norfolk.

Det Supt Julian Gregory said: "We are bringing in some specialist equipment, sonar, which will give us a map of the bottom and reveal any objects down there."

The search may be continued up to Breydon Water, where the rivers from the Norfolk Broads meet and lead into the Yare.

The equipment will provide a computer image of the riverbed and can search up to 10 miles a day.

Mr Gregory said: "We want to make contact with people who use the harbour for recreational fishing, whether or not they were there over the weekend. Please contact us.

"There are people who use the river who may have seen or heard something in the past or over the weekend that may be of relevance to us. One of the options is, he has come to harm because of criminal activity.'

Daniel was last seen by his parents David, 41, and Paula, 30, at about 5pm last Saturday.

CCTV footage from a convenience store close to his home showed him running an errand for his mother at 5.02pm, after which he returned home.

Shortly afterwards, he left home on his bicycle.

Footage from a security camera on the forecourt of a Texaco garage a few minutes' walk from his home showed a boy crossing the forecourt on a bicycle at 5.20pm.

Mr Gregory said: "It's a young lad who looks very similar to Daniel and the cycle is similar.'

Two members of the public discovered the abandoned bicycle next to the fast-flowing River Yare at 3am on Sunday and immediately reported it to the police.

Police have received two unconfirmed sightings of the boy between 7pm and 8.30pm on Saturday by residents of the estate where Daniel's family live, said Mr Gregory.

More than 100 officers have been taking part in daily searches of the beach area, riverside, town and industrial estates.

Specific searches have taken place at the Great Yarmouth Pleasure Beach, which is a "magnet' for children. A police helicopter searched over the town and further afield, while specially trained civil protection volunteers searched the beach.

A fire service crew used a hydraulic platform to check for any sign of the boy at a metal scrapyard close to the dockland and industrial area where the bike was found.

Coastguards said their search for Daniel - of the sea and inland waterways of Great Yarmouth with up to 50 members of the RNLI - was one of the biggest they had carried out.

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

Coastguards were walking and using vehicles to scour the coast to the north up to Hembsy six miles away and to Lowestoft in the south, which is eight miles away.

A senior coastguard with 25 years experience of the waterways around Great Yarmouth said if Daniel had gone into the water it was possible his body may never be found.

Mario Siano, watch manager with the Maritime and Coastal Agency in Great Yarmouth said: "We have had two or three people in the past go overboard on cruises and someone who jumped overboard after his dog, who go down and never come up.

"If a body isn't snagged on the river bed it is likely to resurface in the current conditions in between three and five days.'

Mr Siano stressed that bodies in the water were usually found.

He said it was possible a body which fell into the River Yare in the town could now either be in the sea or on the Norfolk Broads.

Police will continue their extensive searches of the waterways, town and beach area of Great Yarmouth in their hunt for Daniel.

Mr Gregory said Daniel's parents were working hard with detectives to try to find any information that could lead them to Daniel.

Mr Gregory said the search was not being scaled down.

"We certainly have no plans to scale down our resources. We will start to think about that when we have exhausted everything we can do. The longer he is away the more we are worried. But there is still hope.'

Officers have received between 400 and 500 calls from the public in connection with the investigation but police have no new leads, he said.

Daniel's parents have considered every eventuality but there is still optimism he can be found.

He said: "They have been very helpful and have been in quite extensive talks with some officers and have been going through his life with a fine tooth comb to see if there's anything we can glean from that.'