UK police said Tuesday they were trying to locate the parents of three young children who were all abandoned separately as newborn babies, after a judge lifted reporting restrictions on the case.

Formal investigations were launched after each discovery in 2017, 2019 and January this year, when a baby girl was found dumped in a shopping bag in freezing conditions in east London.

But it can only now be reported that all three cases are linked, and that the children -- two girls and a boy -- are related.

DNA testing of the youngest child, named Baby Elsa by hospital staff, showed she has a brother, Baby Harry, and a sister, Baby Roman, who were found in the same area in similar circumstances.

The Metropolitan Police has been trying to trace the children's parents "so far without success", said Detective Inspector Jamie Humm.

"We understand the significant public interest that will come following the lifting of restrictions that allow this information to be reported," he added.

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

Officers have worked around-the-clock probing each case. "We continue to investigate, and will consider the next steps in our investigation," Humm said.

A family court judge on Monday approved the release of details about the cases, lifting the normally strict reporting restrictions on minors and family matters in the interests of "openness of justice".

"There is a clear public interest in reporting this story," said judge Carol Atkinson, granting an application by two UK media outlets to report the link between the three siblings.

"The abandonment of a baby in this country is a very, very unusual event and there are years where there are no children abandoned, and because of that it is the story of the abandoning of a child that is of public interest."

Elsa was believed to be less than an hour old when she was found by a dog walker in the East Ham neighbourhood on January 18.

Her sister, Baby Roman, was found in similar circumstances in a play area in Newham in late January 2019, as freezing temperatures and snow gripped the capital.

Meanwhile in September 2017, Baby Harry was found wrapped in a white blanket in Plaistow.

Harry and Roman -- not their real names -- have since been adopted, while Elsa's future care has not yet been finalised.