Bank of England Governor Mark Carney on Friday dismissed Boris Johnson''s claims that there would be a "standstill" trade arrangement, in the event of a no-deal Brexit.
Johnson, who is leading the race to become Britain''s next prime minister, had argued this week that current arrangements would continue after Brexit, citing the General Agreement on Tariffs and Trade (GATT) article 24 of the World Trade Organisation treaty.
"There will be no tariffs, there will be no quotas because what we want to do is to get a standstill in our current arrangements under GATT 24, or whatever it happens to be, until such a time as we have negotiated" a free trade agreement, Johnson had said in a televised debate on Tuesday.
However, Carney flatly denied that this would be the case in an interview with BBC Radio 4 on Friday.
"The GATT rules are clear. GATT applies if you have an agreement, not if you have decided not to have an agreement or have been unable to come to an agreement," Carney said.
The BoE chief added that, if the EU wanted not to apply tariffs to British goods, then it would have to lower tariffs also to the rest of the world.
"We should be clear that not having an agreement with the EU means there are tariffs automatically because the EU have to apply the same rules to us as they apply to everyone else," Carney continued.
"We should be clear that ''no deal'' means ''no deal'' - it means there is a substantial change in the trading relationship with the EU.
"That may be the choice that the country takes but it should be a choice that is taken with absolute clarity in terms of what that means."
Former London mayor Johnson, who spearheaded the successful Leave campaign in Britain''s Brexit referendum three years ago, will now face Foreign Secretary Jeremy Hunt in a nationwide vote of Conservative Party members.
The winner will become leader of the Conservatives and succeed Theresa May as prime minister, tasked with guiding the country through Brexit.
The BoE had warned Thursday that the prospect of Britain crashing out of the EU without a deal has risen since last month, as it kept interest rates unchanged at 0.75 percent.
During the 2016 referendum campaign, Carney had consistently argued that Brexit would have a negative impact on the nation''s economy and spark a possible recession, in claims which were denied by Brexiteers.
The BoE chief will step down on January 31, having extended his tenure twice owing to uncertainty surrounding Brexit. Britain is scheduled to leave the European Union at the end of October.