Retail sales rose both by value and volume year on year in December, the latest retail data from the Office for National Statistics shows.

Year-on-year sales were up 3.1% by value and 2.6% by volume, excluding fuel.

In the last three months of 2018, sales grew 3.5% and 2.9% by value and volume respectively, compared to the same period in 2017.

However, the ONS said December figures were down 0.9% in terms of both value and volume compared to the previous month.

Contrary to other benchmarking figures, the ONS reported total retail growth of 13.1% in November, slowing to 9.8% in December, which it said showed “a shift in spending to earlier in the year”.

Online sales as a proportion of all retailing jumped to 20% in December, which represented year-on-year growth of 13.9%. The ONS said online sales grew month on month in December, except for in household goods where there was a 17.9% fall, following strong Black Friday promotions.

The data also includes figures from Cyber Monday sales. ONS head of retail sales Rhian Murphy said: “Following the increased growth in November, where shoppers snapped up more Black Friday offers as they continue to bring forward their Christmas shopping, retail sales weakened in December.”

In terms of annual growth rates, 2018 increased by 2.7% in terms of volume.

Deloitte head of retail Ian Geddes added: “Christmas arrived late for retailers, but it wasn’t cancelled. December’s figures clearly show some of the effects of heavy discounting from retailers, both in the run-up to Christmas where the average pre-Christmas discount reached 48%, and Boxing Day sales thereafter.

“A record proportion of sales were made online over this period: 20% of overall sales, making December 2018 the most digital Christmas ever. It is worth acknowledging that the period includes Cyber Monday, the biggest on record, which may have boosted overall sales and could explain why December had a slow start for many retailers.

“This slowdown highlights a shift in consumers making many of their Christmas purchases before December.”