WASHINGTON/MEXICO CITY (Reuters) - U.S. Democratic leaders rebuked President Donald Trump on Thursday for saying Mexico will pay for a border wall through a new trade deal, while Mexico’s new president said the topic has not come up in his talks with Trump.

FILE PHOTO: Mexico's new President Andres Manuel Lopez Obrador arrives for an event to unveil his plan for oil refining, in Paraiso, Tabasco state, Mexico, December 9, 2018. REUTERS/Alexandre Meneghini

The Republican president vowed during the 2016 U.S. presidential campaign to build a wall along the border with Mexico to slow the flow of illegal immigration, and he has long pledged that Mexico - not U.S. taxpayers - would fund it.

In a Twitter post early on Thursday, Trump said that unspecified savings for the United States as a result of the renegotiated trade deal between the United States, Mexico and Canada would pay for the wall.

“Just by the money we save, MEXICO IS PAYING FOR THE WALL!,” he wrote.

While some U.S. businesses stand to benefit from a renegotiated North American trade deal, it was not clear what Trump was referring to in terms of savings for the U.S. government.

Funding for the border wall has been a sticking point in spending bills before Congress, and Trump clashed with leading Democrats over the issue during an Oval Office meeting on Tuesday.

One of them, House of Representatives Democratic leader Nancy Pelosi, ridiculed Trump’s assertion on Thursday.

“What money? What money? ‘That money will be used to pay for the wall?’ The money that businesses make? What money is he talking about that’s going to go pay for the wall? It just doesn’t measure up,” Pelosi told reporters at the U.S. Capitol.

Senate Democratic leader Chuck Schumer taunted Trump over his Mexico claim in a riposte on Twitter.

“Mr. President: If you say Mexico is going to pay for the wall (which I don’t believe), then I guess we don’t have to! Let’s fund the government,” Schumer wrote.

In Mexico City, Mexican President Andres Manuel Lopez Obrador said the border wall was not discussed on a phone call with the U.S leader on Wednesday. Mexico has repeatedly rejected Trump’s demand it pay for the wall.

“We have not discussed that issue, in any conversation. ... It was a respectful and friendly conversation,” Lopez Obrador told reporters after Trump’s tweet linking the trade deal to wall funding.

Instead, he said the two leaders spoke about the possibility of creating a joint program for development and job creation in Central America and Mexico. The White House confirmed the call was about the drivers of migration including insecurity and economic stagnation.

Lopez Obrador said he also discussed a possible meeting with Trump in Washington.

“He invited me. I’m also able to go to Washington, but I think that both for him and for us there must be a reason and I think the most important thing would be to sign this agreement or meet with that purpose,” said Lopez Obrador.