LONDON - British Foreign Secretary Boris Johnson has slammed Downing Street's post-Brexit trade plans as "crazy" in an interview with British media.

According to a report by Daily Mail on Tuesday, Johnson told the newspaper that a "customs partnership" -- thought to be favored by the prime minister -- would involve the UK collecting import tariffs on behalf of the EU.

He branded the proposed customs partnership "crazy" and said it would create "a whole new web of bureaucracy".

It would limit Britain's ability to do post-Brexit trade deals, Johnson warned.

"If you have a new customs partnership, you have a crazy system whereby you end up collecting tariffs on behalf of the EU at the UK frontier," he said.

"If the EU decides to impose punitive tariffs on something the UK wants to bring in cheaply there's nothing you can do," the foreign secretary added.

"That's not taking back control of your trade policy, it's not taking back control of your laws, it's not taking back control of your borders and it's actually not taking back control of your money either, because tariffs would get paid centrally back to Brussels," Johnson said.