The Royal Mail chief executive, Simon Thompson, reappeared before the Business, Energy and Industrial Strategy (BEIS) committee after being asked to clarify statements.

Images shown at the committee on Wednesday showed a bar chart comparing individual postal workers' stop times while delivering and a map with yellow dots that display postal workers' dwell time. The longer a postal worker stands still the bigger the dots become.

Mr Thompson said the data was not used for performance management and is not available in real time. The information used to ensure workloads are "balanced and even" in order to be fair, he added.

When questioned further on the yellow dots measuring dwell time Royal Mail executives said they would check whether there is an alarm that sounds after a minute of a postie standing still.

"So, to the best of my knowledge, that's not the case. Give I am under oath I would like to take the opportunity to check," said Ricky McAulay the operations development director at Royal Mail said.

"I don't believe so either but we'll check," Mr Thompson added.

Witnesses appearing before the committee were given advance notice of the images shown, chair of the committee Darren Jones said at the beginning of the session.

But data from posties' postal digital assistants (PDAs) has been used in 16 conduct cases, Mr Thompson told the committee.

"And the conduct case is a very severe and actually quite a rare occurrence," he said.

"And if that data is requested for that particular situation, then that has to be referred to a human resources professional before that information would be released."

MPs on the committee said they were sent hundreds of complaints and evidence, that called into question answers given by Mr Thompson.

During his last appearance, he denied knowledge of technology tracking employee deliveries. There had been allegations that staff were disciplined based on the data.

Mr Thompson told MPs he was "not aware of technology we have in place that tells people to work more quickly. I am not aware of that at all".

He also denied that it is Royal Mail policy to prioritise parcels over letters, something that could breach rules.

When asked if postal workers had been told to prioritise parcels over letters Mr Thompson said: "No, that is absolutely not true".

Staff at Royal Mail - represented by the Communication Workers Union (CWU) - had engaged in 18 days of strike action during the second half of 2022 over pay, jobs and conditions, including on key shopping days over the Black Friday sales period in December.

That union revealed a fresh mandate for industrial action last week.