Royal Mail has revealed a sharp drop in letter mailing in the busy Christmas season as business worries over Brexit hit marketing post. 

The group said the number of addressed letters tumbled 6% in the nine months to December 25, while letter revenues fell 5%. 

This comes after a 4% fall in letter numbers in the previous six months. 

"We are seeing the impact of overall business uncertainty in the UK on letter volumes, in particular advertising and business letters," Royal Mail said. 

The group signalled an impact from Brexit fears on its letters arm in half-year results in November, when revenues from advertising mail slumped 8%. 

It said the trend for marketing mail revenues had remained "broadly similar" in the third quarter. 

This offset a stronger performance from its parcels business, which notched up a 3% rise in revenues over the nine months to Christmas Day, with the number of parcels delivered up 2%. 

Overall revenues across its UK parcels and letters division fell 2%.

But its European parcels business, General Logistics Systems (GLS), saw a strong festive quarter with revenues jumping 9% over the nine months, helping overall group-wide revenues hold firm on a year earlier.