When the burglars realised the Marie Curie cash - raised from a recent car boot sale - contained a cheque they returned to the scene at Lucille's Kitchen on Catherine Street and slipped it under the door, but kept the money.

Owner Lucille Brolly, who is also chairperson of the Roe Valley Friends of Marie Curie, is amazed the cheque was returned.

"Can you believe it?" she said.

Access to part of the popular eaterie is via a public car park, which also acts as an access point to other shops.

Once inside the premises on Tuesday night, the thieves - who gained access through a skylight - destroyed a cash till, wrecked a filing cabinet, ripped sinks and shelves from a wall which they tore through using a manhole cover.

They fled with a small amount of money from a Marie Curie bucket that was stashed in the office. It is the second time the business has been hit this year.

"I was in tears," frustrated owner Lucille Brolly said.

She can't understand why her premises are being targeted and said she has secured the property as well as she can.

"These boys were desperate to get in, and they are getting off," said Ms. Brolly. "I run a business seven days a week. I knock my pan in and we employ people who want to work and then these thugs come in. Where does it stop?"

Lucille's son, George Brolly, who also runs the business, called those responsible "total scum."

"They're feared of doing a day's work," he said. "They thought they were coming in for a big pay day, but fortunately they were wrong."

George said the break-in has cost several thousands pounds in lost business and damage. The cafe and sandwich bar was closed all day Wednesday, with workmen - builders and plumbers - called in to complete the repairs.

"Hopefully, they're caught," added George of the perpetrators. "They may have slipped up somewhere."

Lucille asked: "Have they got a conscience? That's what I want to know, because they make their living out of hardworking, decent people."

Anyone who saw suspicious activity in the area is asked to contact the PSNI CID office on 0845 600 8000 or Crimestoppers at 0800 555 111.