The regulator, which launched its probe in May, said Royal Mail, owned by International Distributions Services Plc (IDSI.L), was not in breach of its regulatory obligations for the period.

However, Royal Mail's performance so far into the 2022-23 period was "falling well short of where it should be", Ofcom added.

"Our focus remains to restore our service to the high standards our customers expect to receive," a Royal Mail spokesperson said in an emailed statement.

The findings come as the more-than-500-year-old company is under pressure to settle a damaging dispute with its largest labour union over pay and other work policies, warning of severe losses and job cuts if the strike action is not called off.

"Looking back at last year, COVID-19 was clearly still having a significant impact on Royal Mail's operations," Lindsey Fussell, Ofcom's group director for networks and communications, said in a statement.

"However, the company's had plenty of time to learn lessons from the pandemic, and cannot continue to use it as an excuse," Fussell added.

The regulator also said it would closely watch Royal Mail's performance for the rest of the year.