Furious company chiefs have threatened legal action against the official Brexit campaign group over use of their firms' trademarks.
Unilever, Airbus and GE say their logos have been used by Vote Leave as "propaganda" in referendum campaign leaflets to imply their support for quitting the EU.
The bosses accused the official out camp of misleading voters and an act of "bad faith", warning they will take to the courts if the campaign fails to stop.
In a letter to Vote Leave, Paul Kahn, president of Airbus Group UK, Paul Polman, chief executive officer of Unilever and Mark Elborne, GE UK and Ireland president, said: "We were extremely surprised and disappointed that Vote Leave has included our company names and logos in a leaflet that has been sent to millions of British voters ahead of the upcoming referendum on membership of the European Union.
"We would like to make clear that this was done without the permission of our companies, and we have received queries from concerned customers and employees since this leaflet was distributed.
"We believe our companies have been used for propaganda purposes in order to imply our support for exit from the European Union.
"That is not our position; on the contrary, we believe that - for jobs and investment - Britain is better off in Europe, and we have signed letters and made statements in the media to that effect. We consider the misrepresentation of our businesses and the use of our company names and logos to be both highly misleading to British voters, and an act of bad faith towards our companies on the part of your campaign.
"We would like to make clear that, should Vote Leave have sought our permission, we would have refused.
"We would also like to make it absolutely clear that you have no right to use our logos for these purposes, and we request your written undertaking to cease and desist from doing so. Should this reoccur, we shall take whatever further action - including pursuing legal means - we deem necessary, and without further notice.
"If you have any of these leaflets or other material including our logos that have not already been distributed, we insist that these must be destroyed, and must under no circumstances be distributed."
The leaflet depicts the company logos in a "myth buster" about the risk to jobs. It says the businesses have declared they will stay in the UK regardless of the outcome of next week's vote.
Remain supporting Energy Secretary Amber Rudd said: "This is disgraceful behaviour by the Leave campaign."