Amazon appears to be serious about its grocery delivery service in UK. The online retailer plans to rapidly expand the range of products it offers in order to challenge supermarkets such as Tesco, Sainsbury's, Asda and Morrisons.

In November 2015, the e-commerce giant launched Amazon Pantry in the UK exclusively for Amazon Prime members. The service allows customers to fill a box up to 20kg of household supplies including food, drinks, cleaning and laundry, baby and child care, pet, health and beauty products for one-day delivery by paying just £2.99. At the launch, Amazon made more than 4000 items available, and promised to add thousands more.

Speaking to the Guardian, Christopher North, Amazon UK's managing director, said the company wants to grow the Pantry service in the new year by adding thousands of additional products. North said, "We are really happy with the early numbers. In the new year we are going to be adding a lot more products."

Amazon's focus on grocery delivery comes after it posted record sales on Black Friday 2015, its biggest sales day in UK ever. It claims receiving 7.4 million orders on that day, as opposed to 5.5 million in 2014.

"We were a little nervous going into the day, it was a hard record to beat. I don't know how it worked offline versus online, but we have spent six years working out how to hold great Black Friday events. The consistency year in and year out has been important." North added.

Amazon Fresh service, the same-day and early-morning delivery of items including fresh grocery and local products, could be launched in London. The service offers two delivery options – Doorstep and Attended – is available in Seattle, Southern California, Northern California and New York. "When we believe we have got the offer right, and the economics, we will roll it out internationally," North said.