Andres Manuel Lopez Obrador, the sometimes fiery leftist gunning to be Mexico's next president, disputed Trump's anti-migration arguments, saying that crime is actually down in US border cities, that less Mexicans are crossing the border and that deportations have fallen under Trump.

"All this leads me to the conclusion that he is either uninformed or -- I say this respectfully -- that President Trump is using this whole campaign of his to position himself politically in the United States," Lopez Obrador said.

"That is to say, it's pure propaganda," he told supporters at a rally in Nuevo Laredo, on the US border.

Lopez Obrador, a former Mexico City mayor, currently has a double-digit lead over his rivals in the race for Mexico's July 1 presidential election.

Critics accuse him of being a radical who wants to steer Mexico toward socialism, but the 64-year-old has sought to present a more moderate image in his current bid for the presidency -- his third.

However, he has taken a hard line on Trump, whose anti-Mexican rhetoric has strained the two countries' ties.

He has vowed to lead a human chain to protest at the border if Trump follows through on his plan to send National Guard troops to secure it.

Trump's latest attacks on Mexico were triggered by news reports on a caravan of Central American migrants crossing the country toward the United States.

The caravan, which numbered more than 1,000 Hondurans, Salvadorans and Nicaraguans, began breaking up Thursday, after the activists organizing it said it had abandoned its goal of reaching the US border and would end its activities with a rally in Mexico City.

The decision came after four straight days of Twitter diatribes from Trump.

Besides ordering thousands of National Guardsmen to secure the border, the Republican president also threatened to ax what he called Mexico's "cash cow," the North American Free Trade Agreement (NAFTA), if the Mexican authorities did not stop the migrants.