The Government of Western Australia is offering a reward of up to $1 million for information which leads to the location of four-year-old Cleo Grace Smith.
The girl disappeared from a campsite on the state's northwest coast.
Premier Mark McGowan and Police Minister Paul Papalia joined police to announce the reward this afternoon and reassure police they have the full resources of Government at their disposal.
"All Western Australians' thoughts are with Cleo's family during what is an unimaginably difficult time," Mr McGowan said.
"We're all praying for a positive outcome.
"We want to ensure police have everything they need to solve this case and that's why my Government has no hesitation in supporting police with this reward offer."
Police Minister Paul Papalia urged anyone with information to come forward.
"I'd hope most people would willingly come forward if they had information that could assist police, but if this reward motivates someone to help police bring Cleo home, then the Government is more than happy to offer it.
"I know this is every Western Australian parent's worst nightmare.
"I've been advised every available police resource is being directed into this investigation and I've reassured the Acting Commissioner the Government will support police with any request they make to help solve this crime."
Police have acknowledged there is evidence to suggest Cleo was taken from her campsite but insist they haven't given up hope of finding her alive.
It has been confirmed the family's tent was found open at a height Cleo could not have reached when she disappeared from the popular Blowholes site, on WA's northwest coast, in the early hours of Saturday morning.
Her red and black sleeping bag is also missing.
Homicide detectives are assisting local police and investigators have spoken to up to 20 registered sex offenders in the Carnarvon area, but there are currently no suspects.
Detectives are also re-examining nearby shacks along the coastline as the search enters its sixth day.
"There's circumstances around her disappearance that make it very concerning and it's things like the fact that the (tent) zipper was allegedly up so high, the sleeping bag is missing," Inspector Jon Munday told reporters on Wednesday.
"We are hopeful that Cleo is still alive and we're operating on the premise that she is still alive, so we're going to keep searching until we find her."
Inspector Munday said the family were Carnarvon locals and he understood they had set up their tent "in the same vicinity as people they knew".
Cleo's mother Ellie Smith has said the little girl would never wander off on her own and someone must know where she is.
She said she and her partner Jake Gliddon had last seen Cleo about 1.30am on Saturday in the family's tent. They woke around 6am, when Cleo's baby sister Isla wanted a bottle, to discover Cleo was gone and the tent was "completely open".
"She would never leave us, she would never leave the tent," Ms Smith said, describing Cleo as a beautiful and delicate girl with "the biggest heart".
