The detention of a man near the home of a missing three year-old boy is not connected with the police inquiry, officers said.
Mikaeel Kular was last seen going to bed at his family's flat in Ferry Gait Crescent, Edinburgh, at around 9pm yesterday and was discovered missing from his bed by his mother at around 7.15am today when the family woke up.
Police today detained a man in the city's Waterfront Gait but said it was unconnected with the boy's disappearance.
The toddler's jacket and shoes were missing from the property and police are looking into whether he might have left of his own accord.
Efforts are being made to speak to Mikaeel's father, who is understood to be of Pakistani origin
Police Scotland Superintendent Liz McAinsh said: ''There is no evidence to suggest criminality at the moment but clearly we are keeping an open mind.
''We're a big organisation now with Police Scotland and we are using all of the resources at our disposal to look for this three-year-old boy.''
Asked whether she thought Mikaeel might have left of his own accord, Ms McAinsh told reporters: ''We know that his jacket and shoes are not within the property so we are following up all lines of inquiry in that regard. We don't know if he may have left of his own volition, but obviously that's one line of inquiry we are following up.''
Asked whether there were any custody issues with the family, she said: ''Obviously we are following all lines of inquiry, there are no concerns that we have at the moment. We are following all lines of inquiry with all partner agencies and with the family and the family are being very helpful at the moment.
''As you can imagine, Mikaeel's mother is distraught. She just wants our help and the public's help in finding her little boy.''
The police search, which has involved the police helicopter, is focusing on the Pennywell and Muirhouse areas of the city and people are being urged to keep an eye out for the boy.
Mikaeel, who is British with Asian parents, was at home with his mother and four siblings, including his twin sister, last night.
Police asked local residents to look in their homes, gardens and outbuildings and to keep an eye out for Mikaeel in the area and in parks.
Temperatures overnight in Edinburgh dropped to 2.3C (36F) by 4am, according to the Met Office.
Anyone who sees the boy is asked to make sure he is safe and contact police immediately.
He is described as 3ft, of Asian appearance and possibly wearing a beige hooded jacket, blue jogging bottoms, brown Clarks shoes and nightwear.
Ms McAinsh said: ''It was his mum who has reported he was missing to us - she is obviously distraught. He has a wee three-year-old twin sister, so his wee twin is obviously going to be very concerned about where he is.
''It must be awful. As a mother myself I just can't imagine how I would feel if my wee boy went missing.
''Clearly, as everybody out there will be able to relate to, his mother is distraught and she's trying to give us all the information she can to help us in our inquiry.
''We are providing her with all the support that we can through that experience and just trying as best we can with all the resources we have at our disposal to find him safe and well.''
The youngster attends a local nursery and Ms McAinsh said: ''They say Mikaeel is a friendly, playful wee boy and they are obviously concerned for his safety as well and will do everything they can to help us in finding Mikaeel.''
An Edinburgh City Council spokesman said: "Police have been in touch with the nursery and staff are liaising with them."
Anyone with information can contact Police Scotland on 101 or alternatively the charity Crimestoppers on 0800 555111.