UK online retailer Ocado has said it is "encouraged" by the progress of the business so far this year and said it expects gross sales to climb in the second quarter.

In a trading update today (23 May), released ahead of its second-quarter earnings, the firm said gross sales had increased in the 12 weeks ended 13 May.

A spokesperson for the online grocer told just-food that sales growth had accelerated throughout the year. Sales gains had risen to around 13% from first-quarter growth of 10.9%, driven by higher customer numbers and improved order fulfilment, the spokesperson said.

While Easter did fall in the period, the spokesperson added that seasonal factors did not play a "significant" role in the gains.

"Ocado continues to see sales growth increasing as demand for online grocery shopping expands, and our award winning service and increasing range continue to attract new customers," the retailer said.

Operational performance at the firm's Hatfield customer fulfilment centre (CFC) "continues to improve" and is now operating at "record levels" of capacity, it said.

"A number of new enhancements have gone live in both Q1 and Q2 which will enable us to continue to expand our capacity, significantly extend our range, and improve our operational efficiency and customer service performance," it added.

Ocado said the construction of its second CFC at Dordon, Warwickshire, is "progressing according to plan", with testing and commissioning due to start over the summer. Operations are scheduled to commence in the first quarter of 2013.

Year-on-year, however, sales gains have slowed. In the comparable period of last year sales rose by around 22% and sales for the first half of 2011 were up 20%.