The second round of renegotiation talks for the North American Free Trade Agreement (NAFTA) have come to an end after five days of meetings in Mexico City.

Representatives from the US, Mexico and Canada took part in more than two dozen working groups involving trade experts and technical officials, with the aim of advancing discussions and putting forward new proposals to modernize the deal in line with the objectives of the US government.

A statement from US trade representative Robert Lighthizer struck a positive note, indicating that "important progress was achieved in many disciplines", but the threat of the US pulling out of the deal entirely remains on the table.

Canadian foreign affairs minister Chrystia Freeland and Mexican secretary of the economy Ildefonso Guajardo were also present for the talks, which saw the proposals generated subsequently consolidated into a single text upon which the teams will continue to work during subsequent negotiation rounds.

The third round of talks will be held in Ottawa, Canada, from September 23rd to 27th, with all three participating countries agreeing that the process should ideally be concluded before the end of the year.

The stated goal of the NAFTA renegotiation is to provide greater benefits for all three member countries, but the US remains the party with the most sceptical stance, as president Donald Trump has repeatedly criticized the deal as part of the protectionist agenda he has championed since taking office.

Subsequently, US commerce secretary Wilbur Ross repeated that the US is willing to pull out of NAFTA if its objectives cannot be met.

Mr Ross said: "The president has made clear if they don’t work, he’s going to pull out. That shouldn't be a shock to anyone, and really that's the right thing. We need fixes to this deal. It has not worked the way it was intended."