Peak parcel volumes at Royal Mail Group were up 4% year-on-year, with the post and parcel giant handling 120 million in December alone.

Despite a 3% increase in parcel volumes, parcel revenue remained flat in the nine months to 28 December 2014, the operator said in a trading statement today.

It attributed the growth in volumes by rising imports and targeting new business sectors in its account parcels division. It also planned heavily for the peak period, with the opening of 10 temporary sorting hubs and training around 19,000 additional staff.

Volumes in its Parcelforce Worldwide business were up 10%, but the company claimed that pricing continued to be under competitive pressure in the express delivery market.

Royal Mail said it had traded “in line with expectations” during the period, which saw group turnover increase by 1%, but flat revenue in its UK Parcels, International and Letters (UKPIL) business.

It also sold its former Paddington site in December, generating gross cash proceeds of £111m.

Chief executive Moya Greene said: "We are continuing to bear down on costs and expect that underlying operating costs before transformation costs in UKPIL will be flat for the full year. Given our performance over the Christmas period, we are confident that the outcome for the full year will be in line with our expectations."

Regulatory body Ofcom is currently investigating whether last year’s proposed increase in the price Royal Mail charges third-party carriers to make final-mile deliveries were lawful under the Competition Act.

A spokesman for Ofcom told that the investigation is ongoing with an outcome expected in the spring.