Police said Middle Brother State Forest and surrounds will be searched from Thursday morning. The focus of the search since William went missing last Friday morning has been the Kendall State Forest and the area around Benaroon Drive. 

Superintendent Paul Fehon said the State Emergency Service's volunteers will walk the forest's trails as they search for part of a vehicle that may have become detached. 

Teams of emergency services began the first of a two-day search of roadsides ‘‘in case something has been thrown’’, said NSW Police Rescue Sergeant John King.

‘‘It will be a sweep search of the side of the road,’’ he told volunteers at a briefing in Kendall on Thursday.

Sgt King told volunteers not to give up hope.

‘‘We look at those statistics and this is a stand-alone case, so we still hold promise and we are going to continue with that attitude,’’ Sgt King said.

Yesterday police have again appealed for those with information about William Tyrell's disappearance to come forward.

Responding to reports of a person asking Kendall businesses about the whereabouts of Benaroo Drive on Friday, Supt Paul Fehon said investigators were continuing to examine all leads.

"We need to go through that information, collate it, analyse it and we need to substantiate or discount that information that's provided to us," Superintendent Fehon said.

Investigators remain open-minded to William's whereabouts as there is "no indication whether young William is out in the bush or whether other forms of human intervention have been involved," Superintendent Fehon said.

Police have asked anyone who knows a person or car that was using Benaroo Drive or in Kendall on Friday to contact Crime Stoppers on 1800 333 000.