Treasury permanent secretary James Bowler has told MPs an investigation is being launched into the alleged leak of a private Office for Budget Responsibility forecast suggesting the government will need to raise extra revenue next month.
Bowler's pledge came at a meeting of the Treasury Select Committee held at the government's Darlington Economic Campus yesterday afternoon.
It followed a report from news organisation Bloomberg claiming sources had told it that the latest OBR forecast provided to the Treasury projected weaker economic growth. Bloomberg said the figures added weight to the view that chancellor Rachel Reeves will have to find additional funds if she is to stick to her fiscal rules of covering day-to-day spending with tax income.
The OBR's next public report is not due until 26 March, and the forecast at the centre of the alleged leak is understood to relate to preliminary data for Treasury officials and ministers that will be subject to further updates in the coming weeks.
However, Bowler told MPs he was aware of the Bloomberg story and said the suggestion that there had been a leak was being taken "very seriously indeed" with the launch of a probe.
"We will be investigating and following that up as a potential leak," he said. "it's important to put a ring round these forecasts, making sure they're not in the public domain."
Bowler said interim economic and fiscal reports provided by the OBR to the Treasury were not intended for public consumption, and were not the same as the public forecast due next month.
"It's vital that the government and the OBR have the private space to develop our forecasts, economic and fiscal, in time for an OBR forecast," he said.
"The OBR, ministers and officials need to interact as new information becomes available and they need to that in privacy.
"The right thing to happen is for the OBR forecasts to be published for the first time – on 26 March in this case – and for government to respond to parliament as the chancellor intends to do."
Bowler said the OBR had done three rounds of private economic and fiscal forecasts for ministers and officials ahead of its periodic public reports.
"You really do not want to be giving a running commentary on that or, indeed, publishing things as they go along," he said. "Because that would be extremely market sensitive, actually, and therefore deeply unwelcome."
Treasury Committee chair Dame Meg Hillier told the session she did not believe there had been previous incidents of an OBR report being leaked in the watchdog's near-15 year history.
She asked Bowler how many people at the Treasury were likely to have access to private OBR reports. The permanent secretary declined to offer a figure.
Hillier speculated that the number would be in the region of 50 to 100 people.
This morning, the chancellor received a boost when Office for National Statistics figures relating to the October-December period showed growth of 0.1%, helped by the construction and services sectors.
Analysts had predicted a contraction of roughly the same magnitude.