Police have released CCTV stills of a man they want to identify after a tourist had �5,000 of jewellery stolen at King’s Cross Tube station.

The Californian woman, 73, was on her way to Heathrow with her husband when her bag was taken. It also contained their passports and her driving licence.

The woman had accidentally left the bag on a bench on the Piccadilly line platform when she boarded a train.

By the time she realised her mistake and returned to the platform, the bag had gone.

Det Con Eloise Lock, of British Transport Police, said: “The victim received a letter in the post returning the passports and her driving licence a few days later. The letter was posted in the Greenwich area, and I am appealing for anyone who may have come across the documents to contact us.

“The theft has caused the victim a great deal of distress as the jewellery had sentimental value to her.

“Anyone who recognises the man in the images, or the jewellery that was stolen, is asked to get in contact.”

The man is thought to be in his early 20s and is of Mediterranean appearance with a slim build. He was wearing a grey Adidas tracksuit with a baseball cap, a yellow high-visibility vest and a black Adidas rucksack.

Anyone who recognises the man in the image or who has any information which may assist the investigation is asked to call British Transport Police on 0800 40 50 40, quoting incident number B13/LUA of 12/7/2011, or Crimestoppers anonymously on 0800 555 111.