By David Ljunggren

OTTAWA (Reuters) - The leaders of Mexico and Canada will hold talks this weekend on the potential impact that a Donald Trump presidency could have on the NAFTA trade pact, a source close to the matter said on Thursday.

Prime Minister Justin Trudeau and Mexican President Enrique Pena Nieto will meet on the sidelines of an Asian regional summit in Lima, Peru.

They intend to speak to each other more frequently about their NAFTA strategy in the months to come, said the source, who declined to be identified given the sensitivity of the issue.

Trump, who takes office in January, says he will either tear up or push to renegotiate the trilateral North American Free Trade Agreement, under which Canada and Mexico both send the vast majority of their exports to the United States.

"The two men will run through a number of scenarios in Lima and talk about how to address them," said the source.

"They will hold more frequent talks on NAFTA in the coming months as the president-elect's plans become clearer."

The Mexican government later said in a statement that Economy Minister Ildefonso Guajardo will meet Canada's International Trade Minister Chrystia Freeland in Lima on Friday to discuss "issues of regional interest" in preparation for a meeting between Pena Nieto and Trudeau at the summit.

It did not provide further details on the leaders' meeting.

Trump is working with close aides to decide who should get key jobs. His key transition officials do not yet have access to detailed briefing documents on national security and economic policy.

The source said it was too soon to say what, if any, common front Canada and Mexico would take to defend NAFTA, given neither country had any idea what Trump's intentions were.

Canadian officials say that if Trump walks away from NAFTA, Canada could fall back on an earlier 1984 free trade deal with the United States.

There are no such options for Mexico, which Trump has also singled out over what he says is the problem of illegal immigration. Trump made building a wall on the U.S.-Mexico border a central issue of his campaign.

(Reporting by David Ljunggren; Editing by Cynthia Osterman and Kim Coghill)