Tesco has said its online sales grew by 15 percent last year, as it moved towards more precise delivery slots and developed smartphone apps.

As the UK’s largest retailer announced profits up 11 percent at £3.54 billion for the year to 26 February, on the back of £61 billion revenue, it said its web business had grown “strongly”.

The supermarket reported that online grocery sales in the UK alone grew by a “double digit” percentage, with a 30 percent growth at Tesco Direct which sells electrical goods and furniture.

However, online profits only grew “modestly”, it said, as it “chose to invest” in providing shorter delivery slots in London, and added services such as click and collect.

The company drew attention to its iPhone app, which it said “now accounts for 12 percent of [online] customer traffic”. The app allows shoppers to scan the barcode of groceries anywhere and they are automatically added to their Tesco online basket.

In January, Tesco named Mike McNamara as its new chief information officer. Former IT director Philip Clarke is the company’s new chief executive.

The company has invested heavily in IT over the years, and this has played a strong role in improving sales, the supply chain, and efficiency. Among other systems, it has an in-house designed supply chain application, running on IBM system p servers based on Unix. In its results today, Tesco said it had also spent heavily "replatforming" its banking business.