The stakes are particularly high for Texas and other border states, where trade with Mexico is worth hundreds of billions of dollars a year.

The remarks come amid ongoing discussions between the Trump administration and Mexican and Canadian officials.

US President Donald Trump has said he will follow through with his threat to hit imports from Canada and Mexico with 25% border taxes, known as tariffs, on 1 February. But he added that a decision about whether this would include oil from those countries has not yet been made.