LONDON (Reuters) - Hundreds of British civil servants received unauthorised access to potentially market-sensitive data earlier this week before it was officially released, the country’s statistics watchdog said on Friday.

Workers are seen walking during the lunch hour in the City of London, in Britain, January 21, 2016. REUTERS/Toby Melville

The UK Statistics Authority called on Britain’s employment ministry to explain why a comment about monthly jobs data was sent to public employees shortly before its release on Wednesday.

The data showed a strong jump in employment twinned with a slowdown in wage growth, key metrics for the Bank of England as it gauges when to raise interest rates.

“The substance of (the) release was shared by the Department for Work and Pensions with up to 300 people, through a social media network ... by someone who is not approved to have pre-release access to the statistics,” the UK Statistics Authority wrote to the DWP.

A DWP spokeswoman said only a general statement about the data was shared widely, less than 10 minutes before the official release of the full numbers, and that it had taken steps to reduce the risk of a repeat.

Financial market traders have in the past expressed concern that market-sensitive economic data got leaked before its release time, though there has been little direct evidence of this.

Wednesday’s data gave mixed signals on the economic outlook, and sterling hardly moved in the run-up to the release, though 10-year gilt yields did dip to a nine-month low.

“While the authority has no evidence to suggest Wednesday’s breach resulted in any specific adverse reaction, the case highlights the risks of failing to follow appropriate release practices,” a source familiar with the breach said.

The statistics watchdog is separate from the Office for National Statistics that publishes most official data. It wants to end the system under which British ministers and their closest advisors receive 24 hours’ advance access to most key economic data.

“The Authority is deeply concerned about the impact that breaches relating to the unauthorised, widespread sharing of statistics before their publication may have on the trustworthiness of the UK’s official statistics system,” it said on Friday.

The watchdog received 15 reports of data released early in the first nine months of 2015, and 32 in 2014, not all of which are market sensitive.

The watchdog’s last public complaint was in June 2014, when it criticised the country’s finance ministry for revealing trade data to over 400 officials 40 minutes before its release.