Officers investigating the disappearance of April Jones have until Friday afternoon to question abduction suspect Mark Bridger.
They have until 5pm to charge or release Bridger - unless they apply for a further warrant of detention.
Mark Bridger is still being questioned by Police but is yet to be charged
With no sign of April since Monday evening, search teams worked through the night in the hunt for the five-year-old.
Their efforts were spurred on by pink ribbons of hope, donned by hundreds of well-wishers in the close-knit community.
Small expert teams combed areas of thick forest in the mountains around the town as support and messages were sent from across the UK.
April Jones has been missing since Monday
Police are holding Bridger at Aberystwyth police station. They are trying to piece together his movements from 5pm on Monday until his arrest at 3.30pm on Tuesday.
April was seen willingly getting into what is believed to be a Land Rover Discovery on the Bryn-y-Gog estate where she lives at 7pm on Monday.
Bridger, 46, from Machynlleth, drives a Land Rover Discovery which was seized from a local repair garage on Tuesday and fast-tracked for forensic examination.
The distinctive blue landrover was in a repair garage
Expert search efforts have focused on a small farmhouse in the nearby village of Ceinws where he was known to be most recently living.
Search teams began lifting up paving slabs outside the property while activity continued inside.
Police officers search outside a house called 'Mount Pleasant' in the village of Ceinws, believed to be the last known residence of suspect Mark Bridger
Along the fast-moving River Dyfi teams were scouring the area.
More than 2,500 calls with information have been received by police in response to their appeal on Wednesday.
Residents across the small Mid Wales town of Machynlleth wore the pink ribbons in a symbolic gesture of continued hope.
The show of solidarity came in response to a plea from April's mother, Coral Jones, to wear her daughter's favourite colour.
As the family's nightmare continues, residents decorated their cars, homes and clothes with the pink ribbons.
"It is a symbol of the hope that April is going to come back and we are all still optimistic," said Machynlleth Mayor Gareth Jones.
Superintendent Ian John, of Dyfed Powys Police, wore a pink ribbon in a personal show of solidarity.
He said officers from across England and Wales were helping to field calls and searchers were "determined" to find April.
Speaking outside the town's leisure centre, which has become a focal point in co-ordinating local search efforts, John said: "I want to turn to April's family. I'm sure we all are feeling for them at this terrible time, also the friends and the extended family.
"I just want to remind everybody that's why we're here tonight, in the pouring rain in Machynlleth, to focus on the search and do everything that we can to bring this operation to a conclusion."
He added: "I think what we've got to hold onto is that we continue our search, and the good news is that everybody is determined to follow this through."
Bridger was walking in the direction of Machynlleth when he was detained by police
The community continued to hold its collective breath while waiting for a breakthrough in the search efforts.
But the overwhelming effect of April's abduction left residents on the edge of despair.
Prime minister David Cameron added his voice to the chorus of appeals for anyone with the smallest piece of information to come forward.
He described the ongoing ordeal as "every family's nightmare" and urged people to "talk to the police".
"My heart just goes out to April's family," he said. "This is every family's nightmare, having this happen, and the fact that she suffers from cerebral palsy, something I know a little about from my own children, only makes this worse."
It is the fourth day of the search for missing April
April's older sister, Jasmine, 16, spoke for the first time, telling Sky News: "I just want our beautiful princess home now. It's been too long.
"Knowing someone knows something but won't say it makes me feel even worse."
One of the world's leading forensic psychologists who advised British and Portuguese police in the search for Madeleine McCann is reportedly helping detectives in the April case.
Joe Sullivan is said to have been drafted into the Dyfed Powys police investigation team to give advice on interviewing Bridger, The Times claimed.