A new report by KPMG warns banks must tread carefully with mobile banking or risk annoying their customers, even as it forecasts a brisk take-up of such services.

It also recommends financial institutions be more open; while many do already offer APIs, they need to collaborate more with developers.

The report, which uses survey data supplied by UBS Evidence Lab, says banks should investigate the potential of value added services, for instance how virtual customer support can bring branch-style services to a user’s mobile device. But beware annoying customers with too much spam, it adds.

While mobile banking offers many opportunities for cross-selling other financial services, unwanted sales messages can invade what the report terms “device intimacy” and lead to customer complaints, a reduction in usage or even switching to another bank, a totally counter-productive outcome.

KPMG also has a firm prediction for how mobile banking will flourish in coming years: the number of users will double to 1.8 billion by 2019, it forecasts.

The report urges banks to explore areas such as virtual support, social media banking and life tools, for instance cloud storage. The financial sector should also consider mobile-enabled technologies such as wearables and augmented reality as they become mainstream.

Unsurprisingly, security is key, according to KPMG. Forty per cent of consumers are uncomfortable about entering card details in mobile devices, and the possibility of losing their device is among the list of anxieties.

“Banks find themselves having to both protect the customer, while at the same time providing seamless and speedy access to their services to ensure greater consumer satisfaction,” says KPMG.

Biometrics is mentioned as a means to back the security of mobile banking, while ensuring ease of access. However, only “a handful of the main banks” approached in the research currently offer biometric-based access for users.