Michel Barnier denied that the measure would amount to a new frontier separating Northern Ireland from the rest of the United Kingdom and stressed that it could not be blamed for undermining the integrity of the United Kingdom.
The question of the "backstop" of Northern Ireland, which is needed in the case of a Brexit without agreement, has led the negotiations for the United Kingdom to leave the EU in a deadlock.
Barnier told Le Journal du Dimanche: "Contrary to what some say, this is not a border we are creating in the Irish Sea to undermine the integrity of the United Kingdom."
Both parties agree that the insurance policy is necessary to avoid the return to a difficult border between Northern Ireland and the Republic of Ireland, a state of the EU.
Mr. Barnier said that, under the support, all cattle sent to Northern Ireland from the rest of the United Kingdom would be subject to veterinary checks, which are already carried out on 10 percent of the animals.
But he said the figure could be reduced to 40 percent if an animal health agreement were reached at a later stage.
In an interview published on Sunday, the French politician said that these controls, among others, were necessary to prevent unauthorized Irish imports of products such as chlorinated chicken.
Poultry meat that is treated with antimicrobial rinses to kill harmful bacteria occurs in the USA. UU But it is prohibited by EU food standards.
The United States and the EU have a long dispute over the product that remains a problem in the trade relations between the two.
Other problems delaying an agreement include the reluctance of the United Kingdom to address the registered designation of origin of food products, such as champagne or Roquefort cheese.