Online spending through mobile devices, including phones and tablets, is expected to grow over three times to surpass £23.1bn mark in 2018, according to a report from retail research firm Verdict.

According to the report, the spending is expected to reach £7.9bn in 2013, which will be driven growing usage of tablets as mainstream shopping device.

The report revealed that along with improving economic conditions, investment from retailers is also helping the growth. The report also found that while tablet adoption is the driving factor in the growth it has has heavily impacted the spending through laptop.

Verdict analyst Matthew Rubin said cannibalisation of spend has had a major impact in market sizes as mobile phones and tablets have become more mainstream shopping devices, often replacing desktops and laptops.

"Mobile phone spend has grown rapidly, though it remains relatively small, while tablet spend has grown from nothing to almost twice the size of mobile phone spend in just the two years to 2012, and that trend has continued into 2013," Rubin said.

According to the report, 38% of online shoppers research goods in store prior to purchasing online.

"However, with only 7% of mobile phone shoppers completing transactions in a store; there is still a major opportunity to convince them to make the transaction through the store itself or through its own website."

"This requires strong customer service and engagement, but with 57% of online shoppers comparing prices between websites, it is also essential that retailers with homogenous products match or come close to pureplay pricing."