Image caption The RBS system requires users to enter a six-digit number sent to their phone

New technology to enable people to withdraw money from cash machines using their smartphone has been unveiled.

Customers who use the Royal Bank of Scotland (RBS) or NatWest mobile banking app can now request cash, up to £100, via their smartphone.

They are given a six-digit code to enter into an ATM to release the cash.

A similar system has been developed by cash machine operator NCR. This requires users to scan a barcode to withdraw the money.

The services are the latest developments in a long-predicted move towards the smartphone becoming a digital wallet.

'Simple and secure'

RBS said that its new system would help customers who had forgotten their bank cards, or who wished to send cash to family members in a hurry.

It would also allow the people to leave their wallets at home in favour of taking a mobile phone, it suggested.

"It is a really simple and secure way to help our customers get cash whenever and wherever they need it," said Ben Green, head of mobile at RBS and NatWest.

The service is available to customers who have downloaded the bank's free app and use the 8,000 RBS, NatWest or Tesco branded ATMs in the UK. Some 2.6 million people have installed it on their smartphone so far, the bank said.

At present, customers using a card can withdraw up to £300. Initially the limit on the cardless withdrawal will be £100.

Hidden code

Access to the app requires a password, and the withdrawal code will be hidden until the user taps the screen. This is aimed at preventing thieves from looking over the user's shoulder to steal the code.

The system is an extension of a RBS service that allowed people whose card had been stolen to access emergency cash from an ATM.

The bank is also unveiling a system which allows customers to make charity donations at its ATMs.

In a separate development, NCR has announced that it has developed software that allows people to scan a barcode on their smartphone at an ATM to release an amount entered in their smartphone.

It is looking for banks and building societies to adopt the software.