The Treasury has declined to comment on whether a Bloomberg story about the bank tax was a Budget leak. A Treasury spokesperson told Reuters: "We do not comment on budget speculation."
The response follows letters from Dame Meg Hillier, chair of the Treasury Committee, to the Treasury and the FCA. The committee published them on 29 October.
The committee says the Bloomberg article ran at 10:45 on Budget day and contained accurate information about announcements made later that day. It says the story appeared to affect bank share prices, and an updated version at 11:03 noted the movements.
Reuters reports that Hillier wrote to the Treasury:
"I would welcome your confirmation that the Department is undertaking work to understand what happened in this case"
Reuters also reports that the Treasury kept its practice of giving some newspapers embargoed early access to announcements. An unnamed person told the agency that officials worked in "military-style compartments", with upgraded Treasury IT so that protected measures could only be seen by those inside each compartment. That account comes from an anonymous source and has not been independently checked.
No substantive reply from the Treasury's permanent secretary or the FCA has been published.