A VICIOUS thug tried to take a terrified woman's engagement ring and forced her to hand over her iPhone on a Tube train full of passengers.

The 33-year-old victim was travelling west on a Piccadilly Line train which had left Acton Town station when the robbery took place.

The robber threatened her with violence unless she handed over her phone at about 6.15pm on February 17. He tried to take her ring before other passengers stepped in and he fled at South Ealing station.

Detective constable Martyn Kemp, of British Transport Police, said: "Although robberies are uncommon on the Tube this was a frightening experience for the victim, who thankfully wasn’t injured.

"The train was busy and we are keen to speak to other passengers on board, in particular the people who intervened before the robber fled.

"I urge anyone who witnessed this incident or who has any information which may help the investigation to get in contact."

The robber is black, male, 5ft 11ins, in his early twenties, with short shaved hair. He was wearing a white top and grey trousers and was travelling with another man.

Anyone with information should call contact British Transport Police on 0800 40 50 40 quoting reference B12 of 23/2/2012. Or contact Crimestoppers anonymously on 0800 555 111.