Negotiators from the US, Canada and Mexico have wrapped up the seventh round of talks over reforming the North American Free Trade Agreement (NAFTA), with no resolution in sight.

Representatives met in Mexico to discuss ways in which the contested free trade pact can be reorganized in a way that is mutually satisfying to all three parties, but only six chapters have been completed so far, with agreement needed on around 30 in total.

US trade representative Robert Lighthizer has expressed concern that progress on the talks will need to be accelerated, given that Mexico is due to hold a general election in July, while the US midterms will follow in November.

Sentiments around the future of NAFTA have also taken a downturn following US president Donald Trump's pledge to introduce harsh new tariffs on steel and aluminum products, sparking fears of a global trade war.

However, Mr Lighthizer gave a more positive impression, saying: "If the political will is there, I am certain that we have a path to a rapid and successful conclusion."