Reuters reported late on Wednesday that Canadian officials are increasingly convinced US President Donald Trump will leave the accord - a severe setback for Mexico's economy, which depends on exports to the United States.

One possible US tactic would be the presentation of a formal withdrawal letter as a means of creating leverage, given that it would likely take six months for the exit to take effect.

However, Mexican officials told Reuters early on Thursday that if Trump triggered the withdrawal process then Mexico would break off NAFTA negotiations, which are scheduled to resume in January.

The peso fell 0.63 percent in morning trading to 19.41 pesos to the dollar.

Among major equities markets, Brazil's Bovespa index led gains in midday trading, thanks in part to solid inflows of foreign capital from investors looking to buy into a nascent consumer recovery in Latin America's largest economy.

"With signs of good international liquidity remaining, Brazil can still be attractive to new resources from foreign investors," brokerage Magliano wrote in a note.

The index had gained 0.35 percent by midday.

Among the biggest winners on the Bovespa was private education company Est?cio Participa??es SA, which rose 2.55 percent to 37.72 reais after analysts reiterated an outperform rating and raised the target price to 43 reais.

Est?cio rival Kroton Educacional SA was the biggest loser on the index, slipping 2.49 percent to 17.99 reais.