Royal Bank of Scotland has started proactively advising business customers how much more the bank could be willing to lend them.

After a successful pilot, RBS and NatWest are now contacting credit-worthy business customers to ask whether they are interested, as the group tries to lend out £20 billion of surplus UK corporate deposits.

The bank said: "The early signs are good – we trialled this with just over 20,000 SME customers and have been able to offer them an additional £1.7bn of credit."

The next stage will see a further 100,000 customers contacted, with further tranches to follow, helped by the recent appointment of 36 regional lending advisers.

RBS said: "Credit extensions are agreed on an individual basis and determined by a number of factors such as affordability and repayment history."

Corporate banking chief, Chris Sullivan, said the group was "pulling out the stops to show businesses how much we can lend to them".