The HSBC unit's free app allows customers to use their iPhones and iPod Touches to view their balances and last 20 transactions, make payments and transfer money between accounts.

Although Natwest, RBS and Ulster Bank all have dedicated iPhone applications, first direct claims that transactional capability makes it the first true UK banking 'on the go' offering.

Matt Colebrook, CEO, first direct, says the app is about making the "banking experience simpler and quicker, allowing our iPhone enabled customers to access key features of our internet banking; whenever they want and wherever they want".

Apps for other smart phones are in the pipeline.

In May HSBC came under attack from the former head of innovation at rival Lloyds TSB for the paucity of its mobile service.

Gardner, an HSBC customer, praised NatWest for getting in ahead of rivals and rolling out an iPhone app, even if it was not particularly impressive or rich in functionality.

"Shoving a poor application out the door - like NatWest have done - is teaching them valuable lessons about how customers like to use mobile," he blogged.

The Department for Work and Pension CTO speculated - seemingly correctly - that HSBC was holding back, waiting for a "big bang" introduction, in a move he considered to be mistaken.