Amazon has reported a decline in net income despite a rise in sales during the first three months of 2013, Digital Spy said.

The online retail giant's net income reached $82 million (£53m) during the period in question, a year-on-year decline of 37%.

However, booming digital sales helped Amazon achieve revenues of $16 billion (£10.3bn) during the quarter, an upturn of 22%. The firm's gross profit margin also rose by 24% to 26.6%.

The dip in income has been attributed to its expansion plans and investment in hardware products, specifically new additions to its Kindle line of tablets and e-readers.

Amazon has been investing in new warehouses to improve delivery times and is rumoured to be developing a Kindle-branded smartphone, BBC News reports.

The firm is also said to be working on a TV set-top box that will stream video over the internet.