The Royal Mail chief executive has been accused of “incompetence or ignorance” by MPs, who are urging regulator Ofcom to investigate whether the company breached legal service requirements.

Parliament’s bipartisan Business, Energy and Industrial Strategy (BEIS) Committee has asked the watchdog to investigate an alleged breach of the Universal Service Obligation (USO), which obliges the postal operator to deliver letters nationwide six days a week.

MPs have accused Royal Mail of prioritizing parcels over letters, claiming the company has “systematically undelivered” parts of its commitments.

Royal Mail chief executive Simon Thompson testified before the committee in January but was recalled last month in an unusual move after he was accused of making an inaccurate testimony.

Thompson then admitted that digital tracking devices worn by postal workers were used to pressure them to work faster and accused unscrupulous managers of using the information in violation of company policy.

Committee chair Darren Jones said he received nearly 1,500 communications after the first hearing, with evidence showing tracking information from Postal Digital Assistants (PDA) worn by workers was “100% were used to discipline and performance management personnel. Thompson has argued that the devices are used to “balance the workload evenly across the team.”

Jones said: “I find it hard to believe that such widespread breaches of company policy and legal obligations can be traced back to a national network of rogue workers conspiring against Royal Mail management.”

The Labor MP said the committee had been “inundated” with evidence “calling into question the accuracy of the answers” Thompson had given. “Frankly, the failures in company policy that Mr Thompson has admitted can only be due to an unacceptable level of incompetence or an unacceptable level of ignorance of what is happening at Royal Mail,” he said.

In a report by the committee, MPs noted that Royal Mail had failed to meet first class delivery targets every year since 2017. The “company’s USO performance was definitely not good enough,” Thompson told lawmakers.

Relations between Royal Mail executives and their workforce have been strained during a month-long dispute over wages and working conditions that has led to strikes. Talks continue with the Communication Workers Union, which represents some 115,000 postal workers.

Royal Mail has threatened to separate its domestic and international business if “significant operational changes” cannot be agreed with unions.

The company also suffered a ransomware attack that crippled its shipments from the UK to other countries. It refused to pay an $80 million (£67 million) ransom, which was subsequently demanded by hackers with ties to Russia.

A company spokesman said: “Royal Mail prides itself on providing universal service and our policy is clear that parcels and letters should be treated with equal importance. We have informed the committee that we will review the consistent application of our letter and parcel delivery policies across the business.”

The company said it would share the findings of the review with Ofcom and dismissed the suggestion that MPs were misled.

An Ofcom spokesman said: “Royal Mail’s recent performance is clearly a long way from what it should be. We are very concerned about this and have asked the company to explain what they are doing to urgently raise the level of service again.”

Ofcom said each April it assessed Royal Mail’s performance over the previous 12 months, adding that the regulator “would not hesitate to take enforcement action where necessary”.