Toyota Motor Corp. has added its voice to warnings about potential Brexit fallout as the deadline for an agreement on the U.K.'s exit from the European Union looms less than four weeks away.

Possible disruption to trade between the U.K. and the EU is Toyota's "biggest concern," the company's Europe chief, Johan van Zyl, said in an interview at the Geneva Motor Show on Tuesday.

BMW AG, which moved forward a planned four-week production stop to coincide with the U.K. leaving the EU, would consider moving some Mini brand production from its plant near Oxford, England, it said in a statement, reiterating previous comments about contingency planning. The company is also stockpiling parts, CEO Harald Krueger told reporters on the sidelines of the event.