A newborn baby found in a shopping bag near a busy junction was "less than an hour old" when she was discovered, police have said.

The baby girl, given the temporary name of 'Elsa', was discovered at 9.13pm on January 18 by a dog walker at the junction of High Street South and Greenway. 

Elsa was found in a shopping bag and in a towel as temperatures dropped as low as a bitter -4 degrees in London, according to the Met Office.

She is believed to be Black or mixed-race, according to Ch Supt Simon Crick, and police are still desperately searching for the child's mother.

He said Elsa is "safe and well" and being cared for at hospital.

"We believe Elsa to have been less than an hour old when she was found. We do not yet know how long she had been there when she was found," Ch Supt Crick added.

Newham Recorder: The infant was found not far from a busy road at the junction of High Street South and GreenwayThe infant was found not far from a busy road at the junction of High Street South and Greenway (Image: Yui Mok/PA Wire)RELATED: Newborn baby found in shopping bag by dog walker in Newham

On the baby's mother, he said: “We are extremely concerned for her welfare as she would have been through a traumatic ordeal and will be in need of immediate medical attention following the birth.

“Trained medics and specialist officers are ready to support her and we urge her to get in touch by phone or walk into the nearest hospital or police station.

Newham Recorder: Elsa is believed to have been found relatively quickly Elsa is believed to have been found relatively quickly (Image: Yui Mok/PA Wire)

“If you are the baby’s mother, please know that your daughter is well. No matter what your circumstances please do seek help.”

He added his thanks to members of the public whose actions "contributed to saving Elsa's life".

Mayor of Newham, Rokhsana Fiaz OBE, said she was "deeply worried" to learn of the baby's discovery.

"That’s why I am so relieved that this precious baby girl is being looked after and doing well in hospital.

"I am so grateful to the resident who called the emergency services last night, as they have literally saved a life.

“Council officers are supporting the police with their investigations, and they are working tirelessly to find the mother as all of us are concerned for her safety and wellbeing which is paramount.

"We are here to help, with plenty of local services available to support her with the sensitivity and care she deserves. Our thoughts are with both the mother and baby at what must be an extremely difficult time.”