Most European Union nations now use a shade of burgundy for their passport covers, and returning to dark blue, used for British passports issued from 1921 to 1988, was regarded as an important symbol by proponents of Britain’s withdrawal from the European Union, or Brexit.

As has been widely pointed out, however, the choice of color was always Britain’s to make. Although European Union regulations dictate certain elements of the passports — they must be biometric, for instance — the use of some shade of red was optional, as part of an effort to promote a sense of unity across the bloc.

“Over the last few months, we have heard ministers happy to come on the media and talk about the new blue passport and the fact that it is an icon of British identity,” the chief executive of De La Rue, Martin Sutherland, told the BBC on Thursday.

“But now this icon of British identity is going to be manufactured in France,” he added.

Mr. Sutherland said he would like to invite Mrs. May and Amber Rudd, the home secretary, to visit his factory and “explain to our dedicated work force why this is a sensible decision to offshore the manufacture of a British icon.”

The decision to change manufacturer provoked outrage among politicians who backed Brexit, and many urged the Home Office to reverse the decision.