OTTAWA — The federal government has a secret economic analysis of the impact of the carbon tax that confirms the parliamentary budget officer’s prior findings, and the budget watchdog said he believes that his office has been under a gag order to not talk about it.

Budget watchdog Yves Giroux made the surprise revelation when appearing as a witness at the House of Commons finance committee, as he faces fierce criticism from Liberal MPs for not proactively disclosing a modelling error made by his office on the economic impacts of the carbon tax.