A couple from Oxford have warned shoppers they might be unwitting targets of a gang of professional thieves operating in the city centre.

Julia Keddle and her husband Martyn Hobbs, of Crescent Road, Cowley, believe they were "marked" by a gang member who saw them withdraw £1,000 in cash from the Chelsea Building Society, in George Street, last Friday.

They were followed to the nearby Coffee Republic shop, where a woman distracted Mr Hobbs by dropping change on the floor.

Someone then squirted ketchup on the back of Mr Hobbs's jacket and while the couple were dealing with the fuss, a man took the bag containing the money.

When they realised it had gone, Mr Hobbs ran outside and bumped into the man who was carrying the bag.

He handed it over without any confrontation then disappeared quickly and Mr Hobbs found the money was still inside.

The men are thought to be of Eastern European origin.

Ms Keddle said: "They must have trailed us from the bank. I have a feeling they were standing behind us when we were buying a newspaper.

"It was an obvious scam to distract us, especially with they way the put ketchup on my husband's back.

"We were very lucky. I was shouting 'we've been robbed' and Martyn was very quick out of the door. I think the way we reacted may have worried them and helped us get the bag back."

"But people need to be aware these people are in the city centre."

The man the couple first saw in the bank and later in the coffee shop was 5ft 7in, in his 50s, with short, dark hair.

The woman, also in her 50s, was 5ft 5in, with medium length hair. She was wearing a leather jacket. Mr Hobbs said the man he caught with the bag was overweight and in his 30s.

He added: "This was a professional gang of three on the prowl. They must have been checking out people in banks.

"We were clearly marked by the chap who walked into the building society."

Insp Richard Brown, the city centre police commander, warned shoppers to keep bags close by when in busy areas. He added: "While we do get thefts of bags from city centre locations, we're not aware of any direct link to cash withdrawals. We will investigate this incident and review CCTV footage."

Anyone with information should call police on 08458 505505 or Crimestoppers on 0800 555111.