Mexico has warned the US against imposing a unilateral tax on Mexican imports to finance a border wall, saying it could respond in kind.
Foreign Minister Luis Videgaray said the government could place tariffs on selected goods from US states reliant on exports to Mexico.
Earlier, US President Donald Trump vowed to start building the wall “soon, way ahead of schedule”.
The US government says it will start accepting design proposals next month.
The US Customs and Border Protection Agency says it will ask companies to submit proposals “for the design and build of several prototype wall structures” on or around 6 March.
A shortlist of the best designs will be drawn up by 20 March, after which bidders will be asked to cost their ideas.
On Thursday US Secretary of State Rex Tillerson and Homeland Security Secretary John Kelly met their Mexican counterparts in Mexico City.
Neither side made any mention of the wall in Thursday’s news conference after their closed-door meetings.
President Trump needs Congressional approval for funding before moving forward with construction of the wall.
