Carmakers in the U.K. could endure "semi-catastrophic" production interruptions if the European Union stops automatically accepting the nation's vehicle certification program once Brexit comes into effect, executives told British lawmakers.

Terms for Britain's departure from the EU will need to include agreements on so-called type approvals for U.K.-made autos so they can still be sold in the bloc's remaining countries, Patrick Keating, Honda Motor Co.'s government affairs manager in Europe, told Parliament's business, energy and industrial strategy committee in London on Tuesday.

EU regulators have indicated that approvals from the U.K. Vehicle Certification Authority "will either no longer hold validity, or not be able to be extended," and Honda may have to look elsewhere for its European regulatory base for British-made cars, Keating said.