Britain’s main measure of wage growth may need to be revised after a large employer failed to supply earnings data on time, the country’s troubled statistics agency has warned.

In the latest sign of its problems with collecting reliable economic figures that the government uses in economic policymaking, the Office for National Statistics (ONS) issued a caveat alongside March’s average weekly earnings data that “as an exception” it was working on “opening up revisions further back in time” for the figures.

“This will allow for late and updated returns we received from one business to be included, as part of improving the quality of these estimates,” it added.

The ONS conceded that such revisions to the figures from one unnamed employer “may have a small impact at a whole-economy level”. The data agency vowed to provide a “full explanation” at the time it publishes the revisions to the data.

The admission from the statistics agency, first reported by the Financial Times, is just the latest acknowledgment of problems with a range of key economic statistics over the past few months, which are relied on by ministers, the Bank of England and the Office for Budget Responsibility (OBR).

It emerges hours before the chancellor, Rachel Reeves, makes her spring statement address to the Commons in response to the OBR’s latest forecasts, when she is expected to announce further cuts to welfare to balance the books.

A separate report on Wednesday outlined concerns about the reliability of another key ONS survey, in this case local employment levels. Researchers have warned that the key data was “volatile” and had significant flaws and limitations, according to the FT.

This follows a warning from the ONS that there were errors in the growth figures it uses to calculate the size of Britain’s economy, resulting from problems with its “factory gate prices” data.

At the same time, the statistics agency is battling to fix problems with the crucial labour force survey, which provides headline unemployment and employment data. The ONS has had to spend millions on temporary workers to fix the survey, which has been described as “virtually unusable”.

Experts have warned that the string of problems with ONS figures have left the Bank of England, OBR and the government “flying blind” given concerns about the reliability of economic data after months of sustained pressure on the agency.

The ONS has admitted that it could take until 2027 to rectify the problems with its labour market survey, which is the official measure of employment in the UK and therefore crucial for policymakers and ministers.

The Bank of England governor, Andrew Bailey, was so concerned about the issues with the jobs survey that he raised it as a “substantial problem” at the annual Mansion House event in the City in late 2024.

The ONS also admitted earlier in the month that it cannot reverse a pandemic-era decision to release official data on the state of the economy before financial markets open because its creaking website could crash.