An armed man threatened to kill a three-year-old with a knife over a mobile phone, police said.

Officers said a woman in her 30s was approached near the parish church in Bromley, south east London, when she was with her daughter on August 26.

The man said he would kill the child if the woman did not hand over her mobile phone, the Metropolitan Police said.

The incident is now being linked with two others: one where three 17-year-old girls were threatened with a knife and had mobile phones and cash stolen in Bromley on August 16 and another where a 37-year-old woman was pushed from behind and her bag stolen.

Detective Constable Chris Day said: “These were terrifying robberies where the suspect targeted women, even threatening a child. We need to trace the person responsible, and would urge anyone with information about these incidents or a potential suspect to get in touch with us.”

Police are looking for a slim black man in his 20s, around 6ft tall with short hair. Anyone with information is asked to call police on 101 or Crimestoppers anonymously on 0800 555111.