Spain and Argentina prepared to do battle in the World Cup final in New Jersey on Sunday as organisers said they were keeping a close eye on smoke from wildfires in Canada.

Lionel Messi's Argentina are bidding to become the first team since Brazil in 1962 to win back-to-back World Cups, while Spain are trying to win a second title after their maiden victory in 2010.

Organisers said they were "monitoring closely" the smoke that has choked skies over large areas of the United States.

"There's been discussion about it, and we have somebody with the National Weather Service that sits in FIFA headquarters there, so we're monitoring closely," Andrew Giuliani, White House World Cup task force executive director, told a briefing.