Staff are said to be angry about the company's actions

They say everyone at the store in Reading, including managers, will be under suspicion until the thief or thieves are "detected and dismissed".

The money, according a report in the Financial Mail on Sunday, went missing at the rate of �5,000 a week between September and February.

Some staff are reported to be angry at the way the situation has been handled.

Instead of bringing the police in and sorting this out properly, the company is hoping staff will inform on each othere M&S staff member

The letter, attached to payslips, encourages staff to inform on other employees they suspect of stealing.

The letter says: "We know that most colleagues are honest, but we also know that many are not.

"We have good reason to believe that some employees steal; merchandise, steal from other colleagues and from tills.

"These losses are off the scale and everyone, including management, is under suspicion until such time as the thieves are detected and dismissed."

'Urgent review'

One unnamed staff member told the Financial Mail: "We are fed up with being treated like this.

"Tills are used by several staff a day and the float isn't checked with each changeover.

"But instead of bringing the police in and sorting this out properly, the company is hoping staff will inform on each other."