There were two other robberies in the area in December 2020 (Credit: Metropolitan Police)
They have also released an E-fit of a man they need to identify based on the description of one female victim.
A man approached the woman and threatened her with a knife while she walking along Roding Valley park trail.
He shouted at her to hand over her phone and the security details of the device.
She gave it to him and he began to run away. Some passers-by witnessed the incident and tried to chase the suspect.
He eventually threw the phone onto a path and continued to run away.
The suspect is described as a black man, aged around 18-years-old. He was wearing a black hat and clothing with a possible blue stripe down the side of his tracksuit trousers.
Detectives are trying to establish if it is connected to two robberies in the same area on Friday, 18 December and Sunday, 27 December 2020.
Any witnesses who recognise the E-fit should call police on 101 quoting reference Cad 5632/24Jan.
To remain anonymous, call Crimestoppers on 0800 555 111 or contact them via crimestoppers-uk.org.
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Tags: Woodford Green, Robbery, Redbridge