A decline in the number of Christmas cards sent in the post contributed to a slump in Royal Mail shares.

Its UK parcels business, however, grew, helped by a better Christmas than the previous year.

Total letter revenue was down 5% over the past nine months with addressed letter volumes, excluding elections, declining by 6%. UK parcel revenue was up 3% with volumes up 2%.

Group revenue was in line with expectations, with 9% growth in international offsetting a 2% decline in UK revenue.

The company’s shares were the worst performer on the FTSE 100, down 5%.

Moya Greene, chief executive Officer, said: “Our cost avoidance programme is on track. We continue to target a reduction of up to 1% in underlying UKPIL operating costs before transformation costs in 2016-17.”

The company said it was seeing the impact of overall business uncertainty in the UK on letter volumes, in particular ‘junk mail’ advertising and business letters.