The head of Royal Mail has acknowledged policy breaches in monitoring postal workers’ delivery speed.

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.

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.

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”.

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

But the chair of the committee Darren Jones said: “Contrary to your evidence, we have been told that managers in many delivery offices are advising Royal Mail delivery workers that parcels are still to be prioritised.”

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.