A 20-year-old man was attacked with CS spray and threatened with stabbing during a robbery in Watford town centre.

The victim was walking through a subway underneath Rickmansworth Road near its junction with Cassio Road at around 8pm on Tuesday when a man approached him and asked the time. He kept walking but the man followed him and then two more appeared.

The robbers threatened to stab him before going through his pockets and stealing an MP3 player, a mobile phone and a cash card.

The victim, who lives in Watford, then tried to get away up the subway steps but was caught by the trio.

They then sprayed him in the face with CS spray.

He hit out at his attackers, who made off through the subway, which allowed him to make his escape and to report his ordeal to the police.

Police say he suffered skin irritation and sore eyes as a result of the CS attack but was otherwise uninjured.

The three robbers are all described as black, aged between 15 and 18, about 5ft 9in tall and wearing dark clothing. Two wore hoods during the attack.

Anyone with information can contact the Detective Sergeant Ian Siggery on 01923 472 490.