Detectives say "no stone is being left unturned" in the search for five-year-old April Jones as officers are given a final 24 hours to question the murder suspect.
Speaking at a news conference, Superintendent Ian John said eight teams of more than 60 specialist officers were now scouring the remote countryside in Mid Wales for the little girl.
He added: "All of the blue light services are involved in the search, including the fire service, ambulance, coastguard, RNLI as well as the RAF mountain rescue service and some 150 members of the Mountain Rescue service from across the UK.
"There are rescue dogs and a host of specialist equipment being used including boats with sonar equipment and the helicopter with thermal imaging capability."
He said he was "completely overwhelmed" by the response from the public who have been handing out food and drink to officers working in "challenging" conditions across the rugged terrain outside the small market town of Machynlleth.
Supt John again appealed for anyone who saw suspect Mark Bridger or his blue Land Rover Discovery, registration number L503 MEP, in the hours between April's disappearance at around 7pm on Monday and his arrest at 3.30pm on Tuesday.
Earlier, Mr Bridger was driven to Aberystwyth Magistrates' Court in a prison van with a police convoy, where an application was granted for a further and final warrant of detention. It gives detectives until 5pm tomorrow night before they will have to charge or release him.
After his 25-minute court appearance, the 46-year-old was flanked by two officers as he was escorted back into Aberystwyth Police Station with a blue blanket over his head.
The latest developments came as April's distraught parents Paul, 43, and Coral, 40, issued three new pictures of their daughter.
Mr Bridger was initially arrested on suspicion of abduction, but detectives announced today that the search had become a murder inquiry.
Police with spades have sealed off an area of shrubland near his rented cottage in the tiny village of Ceinws, close to the Dyfi river - one of several areas being examined in the hunt for the little girl.
Hundreds of volunteers have taken time off work to search for April, but today they were asked to stay away and leave the hunt to experts.
Sky's Crime Correspondent Martin Brunt said: "Clearly it appears that the police are looking for a body and have given up hope of finding April alive."
But one volunteer who has been helping in the search told Sky News: "If they haven't found her yet, there's a chance."
Search teams have been focusing on a number of areas, including a small stretch of the Dyfi River. A specialist sonar boat has been brought in to help teams examining the river bed.
Officers were also collecting vegetation and digging through shale with trowels in an area of river bank the size of a tennis court. They have also been searching a steep river bank where witnesses claim to have seen a man with a bin bag.
Police have confirmed that Mr Bridger attended the same school parents' evening as April's mother and father just hours before she disappeared in Machynlleth. April, who has cerebral palsy, was reported to have willingly got into a vehicle after playing with friends near her home on the Bryn-y-Gog estate.
Mr Bridger was seen at nearby Ysgol Gynradd Machynlleth school, where two of his children are pupils. Witnesses saw the former leisure centre worker drive to the parents' evening, which started at 5pm, in his Land Rover.
Sources close to Mr and Mrs Jones said the couple had been given a "glowing report" about their daughter's progress - and had allowed her some extra play time when they returned home as a treat.
April's family have launched a pink ribbon campaign to support the search. Her favourite colour is now tied in ribbons on gates and doorways in Machynlleth.
:: Police have been flooded with calls from the public about the case, but they continue to appeal for anyone with information to call the Child Rescue Alert Line on 0300 2000 333.
:: Machynlleth Town Council has set up an appeal fund for April and her family. To make a donation send a cheque payable to MTC-April's Fund, Y Plas, Aberystwyth Road, Machynlleth, Powys, SY20 8ER.