More than 30 residents have reported thieves stealing their money or cards at cash machines in less than three months.

Police urged bank customers to be vigilant after seven victims came forward in the first two weeks of March.

They said crooks were targeting residents across the borough, with hotspots including Barnes, Kew and Richmond town centre.

The thieves have used techniques such as the “Lebanese loop”, a plastic strip they insert into the cash machine to capture bank cards. Men and women fraudsters have also distracted customers before taking their money.

Detective Chief Inspector Martin Ward, of Richmond police, said: “So many people are totally unaware of what happens, half the offences don’t get reported.”

Rachel Redmond, 28, told the Richmond and Twickenham Times last year how two robbers stole £200 from her at HSBC, in George Street, Richmond, during her lunch break.

Police said fraudsters were mainly targeting bank customers on Tuesdays and Thursdays, between 4.30pm and 7pm.

British Transport Police issued an alert to commuters last month about a spate of Lebanese loop bank machine scams on the London Underground.

Victims have reported their card getting stuck in the machine before a fraudster offers help, watching them as they re-type their pin code.

Officers advised customers cover their hand when typing their number, do not get distracted, avoid machines where people are lingering and never accept a stranger's help.