A baby girl found in a shopping bag in east London earlier this year is the third child to have been abandoned by the same parents in similar circumstances in the past seven years, British police say.

The baby girl, named Elsa, was discovered by a person walking their dog one night in January near a busy junction in the Newham district, police said.

The baby was wrapped in a towel inside a bag on one of the coldest nights of the year with sub-zero temperatures.

Subsequent DNA tests revealed that Elsa was the full sibling of two other babies who had also been abandoned in the same area.

Harry, the first baby, was found in a park in Newham in September 2017.

In January 2019 another baby, named Roman, was discovered by dog walkers at a children’s play area.

Both were wrapped in blankets and one was in a bag.

Details of the case were made public on Tuesday (British time) after a judge at a family court in east London said the story was of public interest as babies are very rarely abandoned in modern Britain.

The BBC and PA Media were given permission to report the sibling link of the three abandoned children.

The BBC said Family Court documents stated baby Elsa still had her umbilical cord. Doctors estimated she had been born only an hour before.

Although she was extremely cold when found, Elsa was described as crying and responsive. She is now doing well in foster care, the BBC said.

The children will all know they are full siblings, and there are plans for them to have some form of contact as they grow up, the BBC reported.

Baby Roman was found in 2019. Photo: MET Police

Detective Inspector Jamie Humm said police had been working on trying to locate the mother and provide her with support.

“We understand the significant public interest that will come following the lifting of restrictions that allow this information to be reported,” police said.

“It is significant news and our work has focused on trying to locate the mother and provide support to her.”

Despite appeals by the Metropolitan Police, the parents have not been identified.

-with AAP