CASH machine users in Bolton have been warned to safeguard their bank accounts after a series of crude attempted thefts.

Police say thieves insert strips of plastic to prevent cash cards going fully inside machines -- leading users to believe their cards have been swallowed when they are simply stuck.

Customers input their PIN numbers but the machine will refuse to return the cards. Thieves are then able to remove them with wire or thin plastic strips.

Det Sgt John Cook, of the Greater Manchester Police Cheque Fraud Unit, said: "There is usually some interaction between the fraudster and the victim, but the problem with these types of offences is that we do not really know where they are happening.

"I am sure these types of cash machine offences are taking place all over the North-west, including Bolton."

The warning comes after card slots of two cash machines were found to have been deliberately tampered with in Tameside.

Three French nationals were also jailed for seven years in March after an investigation into 1,600 similar thefts at more than 400 cash machines across Britain.

Det Sgt John Cook added: "The technique used to obtain the card often means that people do not realise they have become a victim until they check their balance, days or even weeks later.

"It is important to raise awareness of this type of crime, so that cash machine users can stop themselves becoming victims.

"If a cash machine withholds your card, report it to the bank immediately and make sure that you never disclose your PIN number to anyone."