Police have called off tonight's search for missing toddler Aisling Symes.

By the time they resume searching tomorrow morning, the two-year-old will have been missing for around 37 hours.

Two-year-old Aisling went missing from Longburn Rd in the Auckland suburb of Henderson around 5.15pm last night. She was with her parents at the time, who were cleaning up a family member's vacant home.

Around 100 searchers have been looking for the little girl, including a large team of specialist rescue personnel.

Inspector Gary Davey says there is no evidence of foul play but there is now a police investigation parallel to the search and rescue effort that has involved over 10 staff.

"It would be negligent of us not to look at all aspects of Aisling's disappearance," Mr Davey said.

Asked if police had interviewed any paedophiles living in the area, Mr Davies said he would be looking at any suspicious behaviour and suspicious people in the area.

Police have been searching a rain swollen river which runs alongside the road.

Police divers this afternoon concentrated on the waterways in the Huruhuru Creek and Taikata Inlet. A police dive squad was brought in to help.

"Police have pulled out all the stops," Mr Davies said

He said in addition to the 100 police staff, Hamilton and Whangarei search and rescue were on standby, and the army and air force had also volunteered staff as had the fire service.

Mr Davies said he had spoken to the family several times today and described the situation as "every family's worst fear".

He said a child's t-shirt found in a nearby stream was not consistent with the items of clothing Aisling was wearing at the time she went missing.

It was bitterly cold overnight but one theory police were working on was that she may have been taken in by a young Asian woman who may have spoken to her about the time she was last seen.

Mr Davey said the woman may not speak English well and may simply not understand the fuss the little girl's disappearance would have created.

The woman is described as being in her thirties, approximately 1.65 metres tall and of medium build.

She was wearing a black top with three-quarter length sleeves and had long black hair.

The woman is also described as having a black and grey dog on a lead.

Mr Davey said it was unusual that if someone had taken Aisling in for the night that they had not called police.

"If one of the neighbours had picked her up and was looking after her we would have expected them to have called us by now."

He said they were probably now past the point Aisling may have spent the night asleep in a warm place.

Police spokesman Kevin Loughlin had requested residents of Longburn Rd, Kingdale Rd and Rathgar Rd to check their properties for Aisling, particularly sheds, out buildings, fencelines or other places that a small child may explore or hide in.

Aisling was described as being tall for her age, of European appearance, with light brown hair.

She was believed to be wearing a green jacket or ski jacket, blue jeans embroidered with flowers, and white tennis shoes.

Aisling's father, Allan Symes, told Radio New Zealand he was overwhelmed at the number of people who had turned out to search for his daughter.

"I would just like to say to everyone out there my heartfelt thanks and my wife Angela's heartfelt thanks to all the neighbours, the volunteers, the search teams, fire rescue who are out there who have just turned up.'

Anyone with information about Aisling or her whereabouts was asked to contact the Henderson Police Station on 09 839-0600.