LONDON (AP) — British Foreign Secretary Boris Johnson has attacked Prime Minister Theresa May's plan for a customs partnership with the European Union after the U.K. leaves the bloc — the latest sign of dissent within her Cabinet.

Johnson told the Daily Mail newspaper that the partnership idea was "crazy" and would create a "whole new web of bureaucracy."

The comments come after May's Cabinet last week failed to agree on a preferred option for Britain's future customs relationship with EU. May's preferred option is a partnership under which the U.K. would collect import duties on behalf of the EU for goods arriving via British ports.

Johnson tells the newspaper that May's idea is "totally untried and would make it very, very difficult to do free trade deals."