The members of the North American Free Trade Agreement (NAFTA) have concluded the fifth round of talks over a potential renegotiation of the deal, but a final resolution remains some distance away.

Nearly 30 negotiating groups from the US, Canada and Mexico convened in Mexico City for the discussions, which are taking place due to the US government's unhappiness with the current shape of the deal and its desire for a new-look settlement that it would see as more beneficial to US businesses.

The US, under president Donald Trump, has repeatedly stressed that a failure to compromise on Canada and Mexico's part could lead to the US withdrawing from the pact completely. However, significant differences between the negotiating positions of the three countries continue to persist, with little sign of progress being made.

Mexico and Canada rejected a US proposal to raise the minimum threshold for autos from 62.5 per cent North American content to 85 per cent, as well as to require half of vehicle content to be from the US. Other demands from the Trump administration - including the abolition of a key dispute resolution mechanism and curbs to Mexican and Canadian agriculture - are also being resisted.

A trilateral statement said the latest round of talks resulted in some progress being made in terms of "narrowing gaps and finding solutions", but US trade representative Robert Lighthizer struck a less positive and more confrontational tone.

He said: "While we have made progress on some of our efforts to modernize NAFTA, I remain concerned about the lack of headway. Thus far, we have seen no evidence that Canada or Mexico are willing to seriously engage on provisions that will lead to a rebalanced agreement. Absent rebalancing, we will not reach a satisfactory result."

The sixth round of negotiations will take place from January 23rd to 28th 2018 in Montreal.