A baby found in a shopping bag in east London was less than an hour old when she was discovered by a dog walker, police believe.

The little girl, who has been named Elsa by hospital staff, was found in East Ham on Thursday.

Detectives said the dog walker kept the baby, who is believed to be black or mixed race, warm with blankets thought to have been left with the child.

Paramedics then arrived and checked the girl over before taking her to hospital, where she remains.

She was not injured in any way.

Detectives have appealed for the baby’s mother to come forward, as they are “extremely concerned” for her welfare.

Chief Superintendent Simon Crick told reporters at the scene on Friday: “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.

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

He said the mother will “absolutely” get support from the council and social workers if she comes forward.

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

It is not known whether she is local to the area.

Mr Crick said he was “extremely grateful” to members of the public who stayed at the scene, adding “your actions contributed to saving Elsa’s life”.

He would not give more details about the identity of the dog walker.

Restaurant manager Tania Iurac, 25, who lives nearby, told the PA news agency: “My friend came home from work at around 11pm and she told me a lot of police officers were outside with a dog and the area was closed.

“I was worried. We went outside and asked the police for more information.

“I saw a white towel on the floor. It was clothing. It did not have blood on it or anything. The baby was not in there.

“There was I would say six to eight police officers around. There were a lot of people asking questions.

“I am just shocked.”

A couple walking near the scene on Friday told reporters: “It is sad, very sad. It is shocking. During the daytime people come along this pathway and have never seen anything like this.”

Temperatures dropped as low as minus 4C around London on Thursday night, the Met Office said.

Anyone who knows the mother is urged to contact police by calling 999 and using the reference CAD 6876/18 Jan.