Ocado co-founder Jason Gissing is to retire from the retailer it was revealed as the online grocer reported widening pre-tax losses.

Gissing will leave the board and company at the annual general meeting in May to spend more time with his family and to concentrate on environmental and social issues.

Ocado chief executive and co-founder Tim Steiner said: “I have worked with Jason for 20 years. Jason has led the development of our brand and helped shape the culture inside Ocado and the way we are perceived by our customers.

“He has been an invaluable partner and friend to me and I will miss his daily humour and insights. We all wish him the very best.”

Ocado posted gross sales up 17.2% to £843m last year, when pre-tax losses widened to £12.5m.

Before exceptionals, pre-tax losses stood at £5.1m, compared with a £1.8m profit in 2012. However, EBITDA advanced 35.1% to £45.8m.

Over the year Ocado opened a new fulfilment centre in Dordon and signed a strategic partnership with grocer Morrisons. It launched Morrisons.com using Dordon for fulfilment last month, “improving the Ocado operating economics”. Ocado plans to commit to a new fulfilment centre this year.

Steiner said: “Last year the food retail market in the UK was driven by consumers’ increasing preference for shopping online. Today the momentum seems unstoppable and, as the market evolves, we are leading the way in delivering market-leading service, innovation, and technology to the benefit of our customers. “

“2013 was an extremely busy year for us with significant progress in growing both our customer numbers and average spend thanks to a wider range of products, even better prices, and the fact that we are now even easier to shop.

“We have continued to grow our general merchandise business, adding depth to the range in certain non-food categories and launching Fetch, our specialist online pet store.

“During the year, we also announced a long term agreement with our first strategic client, Morrisons, to provide them with IP and operating services to launch their online grocery business.  

This development reflects the increasing demand for online grocery shopping in the UK and internationally, and a validation of the unique technology, IP and operating model pioneered by Ocado. We are confident that we are well positioned to benefit from future strategic developments as online grocery shopping increases in popularity. ”

Ocado said its number of active customers rose by 30,000 to 385,000 over the year. Growth in frequent shoppers climbed as Ocado focused on new customer acquisition rather than low value customer retention. Average basket spend went up from £112.10 to £113.53.

Ocado co-founder Gissing retires as full-year losses widen