Set up by VocaLink in 2013, Zapp is aiming to bring real-time mobile payments - in store, online and through apps - to millions of Brits by integrating its system into bank apps and tapping into the Faster Payments rails.

In January five major financial institutions - HSBC, first direct, Nationwide, Santander and Metro Bank - committed to embedding Zapp within their phone and tablet apps, bringing the technology to their 18 million customers.

However, as it targets 20 million users by 2017 and promises to rival traditional payments giants such as Visa and MasterCard, the startup is working hard to bring the likes of RBS, Lloyds and Barclays onboard.

Speaking at a briefing today, CEO Peter Keenan said: "We are in varying degrees of discussions with the remaining banks in the UK and are confident of making more announcements in the next few months."

The company is being more tightlipped about retail partners. With just months until the e- and m-commerce parts of the service are set to go live, Keenan is refusing to name any firms that have signed up. However, it is understood that major players in the utility and loyalty industries are on the company's radar.

Keenan is confident that with major banks behind it Zapp will flourish in a hugely competitive market. He insists that rival services such as the telco-owned Weve project are "a good thing" but argues that Brits are more likely to trust and adopt Zapp because of its closeness to banks.

In addition, Zapp CTO Ian Sayers, who oversaw the development of Pingit at Barclays before being poached, thinks that the technology's open-loop structure will also be a key contributor to its success.

Zapp demos the e-commerce element of its application