Reuters news agency says it obtained document after visiting URL it predicted file would be uploaded to

• How Rachel Reeves’s budget was leaked 40 minutes early

The chair of the Office for Budget Responsibility has said he felt mortified by the early release of its budget forecasts as the watchdog launched a rapid inquiry into how it had “inadvertently made it possible” to see the documents.

Richard Hughes said he had written to the chancellor, Rachel Reeves, and the chair of the Treasury select committee, Meg Hillier, to apologise.