Mexican President Enrique Pena Nieto told Donald Trump on Twitter Thursday that he would not pay for the GOP nominee's proposed southern border wall.

"I repeat what I said in person, Mr. Trump: Mexico will never pay for a wall," Nieto tweeted in Spanish at Trump.

Pena Nieto's message responded to a tweet from Trump exclaiming, "Mexico will pay for the wall!"

After meeting with Pena Nieto on Wednesday, Trump said the two men discussed the wall but not who would pay for it. Pena Nieto offered a different account, and said later that he told Trump right away that Mexico would not pay for it.

Onstage in Arizona, Trump told his supporters that Mexico would pay for the wall, but "they don't know it yet." The Mexican president has persistently disputed that Mexico would pay for it.

Trump's first face-to-face meeting with the Mexican leader has since devolved into a Twitter squabble.