Domino's Pizza Group said it expects first-half core earnings to be slightly lower, hit by additional costs during the coronavirus-led lockdown as the company made significant changes to its business. 

It said the costs stemmed from re-routing store dispatches to stop two-person deliveries, ensuring all stores remain closed during restocking, contact-free delivery boxes and issuance of face masks, among others. 

The pizza chain said it was unable to provide full-year guidance and added it was uncertain how long it will have to continue incurring these costs. 

The company said that while sales grew as more people ordered in, it could not offset the extra costs incurred from implementing safety measures. 

"We have also seen a change in consumer purchasing behaviour and average basket composition, with a higher proportion of sides and desserts, which, whilst aiding our sales performance, has impacted our margins," the company said. 

Like-for-like sales in the UK grew 3.7% for the first half of the year to June 14.

But sales at its Irish business fell 5.9%, which the company said was the result of more pronounced weaker consumer spending during the lockdown. 

Domino's, which has been looking to sell its loss-making international operations, also said sales have been particularly impacted in Switzerland, driven by the temporary closure of a number of stores.