Washington, Jul 27 (IANS): US Treasury Secretary Steve Mnuchin expressed optimism on Thursday about reaching accord quickly with Canada and Mexico on revising the 1994 North American Free Trade Agreement (NAFTA).

"We hope to have an agreement in principle, clearly, very soon. That's the first priority," Mnuchin said. "I think we're making a lot of progress."

US Trade Representative Robert Lighthizer, meanwhile, assured lawmakers that negotiations with Mexico and Canada were advancing at an "unprecedented speed", Efe reported.

"Hopefully we are in the finishing stages of achieving an agreement in principle that will benefit America's workers, farmers, ranchers and businesses," he said at a hearing of a Senate Appropriations subcommittee.

Mexican Economy Secretary Ildefonso Guajardo is due in Washington on Thursday for talks on NAFTA with Lighthizer.

Jesus Seade, designated as Mexico's future NAFTA chief negotiator by President-elect Andres Manuel Lopez Obrador, is expected to take part in the conversation.

The process of revising NAFTA got under way in August 2017 at the initiative of US President Donald Trump, who has repeatedly denounced the pact as a "disaster" for American firms and workers.

After successive rounds of talks, the parties remain far apart on key issues such as automobiles and on Washington's insistence -- reiterated on Thursday by Lighthizer -- that the pact include a five-year sunset clause, a demand flatly rejected by Mexico and Canada.