MEXICAN President-elect Andres Manuel Lopez Obrador has issued an open letter to US President Donald Trump, calling for urgent negotiations on the Nafta free trade deal.

His letter was delivered on Sunday to Washington with senior Mexican officials who were meeting their US counterparts.

The left-leaning president-elect, known as Amlo, won the July 1 presidential election in a landslide but doesn’t take office until December 1.

His proposed foreign minister Marcelo Ebrard read out a copy of the letter, which states that the incoming administration's aim is to "start a new chapter in the relationship between Mexico and the United States, based on mutual respect."

It urges a redoubled effort to conclude negotiations and revisions to the 24-year-old North American Free Trade Agreement (Nafta), which also includes Canada.

"Prolonging the uncertainty could stop investment in the medium and long term, which clearly would challenge economic growth," Mr Lopez Obrador wrote.

Renegotiations began nearly a year ago after President Trump demanded the agreement should better serve US economic interests.

US-Mexican talks, which will resume on Thursday, have been stalled for several months after Canada and Mexico couldn’t accept the US administration’s demands, particularly that 75 per cent of all car parts be sourced from the three countries in order to qualify for tariff exemptions.

Since negotiations were halted in May, the Trump administration imposed steel and aluminium tariffs on these imports from Canada and Mexico, citing security risks.

Mr Lopez Obrador said that migration, development and security are the main areas he wants to work on with his US counterpart.

"My government is willing to present to our Congress ... the initiative and budgetary proposal to contribute economic resources and experiences in this joint effort," he wrote.

The progressive leader made clear during the latter stages of Mexico’s presidential campaign that he would concentrate on his country’s internal markets if agreement with the Trump administration proves impossible.

He stressed he was in favour of Nafta continuing, while insisting that its demise “cannot be fatal for Mexicans. Our country has a lot of natural resources, a lot of wealth.”