The Australian soccer federation confirmed on Thursday that a two-match tour of the United States by its women's team has been called off, 24 hours after a union representing the players said stalled contract talks meant the team would not travel to the U.S.

Football Federation Australia chief executive David Gallop told a media conference in Sydney that the players' union, Professional Footballers Australia, made ''extraordinary demands'' which meant the tour could not take place.

The PFA, a union representing male and female players, on Wednesday said the tour had been canceled a day after players refused to show up for a practice session in Sydney.

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The collective bargaining agreement expired in July, and the Matildas - as the women's team is known - have not been paid in two months.

The Matildas, who lost to Japan in the World Cup quarterfinals, are seeking an increase in their 21,000 Australian dollars ($14,475) a year contract to A$40,000 ($28,000).

FFA has refused to increase their salary, which is based over a six-month playing period, to the higher figure, saying the increase was not sustainable.

A U.S. Soccer spokesman on Thursday said 31,000 seats had been sold for each of the matches in Detroit on Sept. 17 and Birmingham, Alabama, on Sept. 20.

He would not comment on Australian media reports that the U.S. association would lose more than a million dollars because of the canceled tour, saying in an emailed response to The Associated Press that ''we do not discuss financials or the specifics of our contracts with other federations.''

Matildas coach Alen Stajcic reportedly spent late Wednesday contacting players to see if they would still be willing to play despite the union ruling.

News Corp Australia reported earlier Thursday that six players, including captain Lisa De Vanna, had broken ranks with the union and still hoped to fly to the U.S. on Friday.

''I just want to play for my country. It's all I want to do,'' De Vanna was quoted as saying. ''If my coach calls me and asks me to play I will always make myself available.''

PFA chief executive Adam Vivian informed FFA of the strike action after a meeting of the team Wednesday.

''The players are currently uncontracted, and are under no obligation to participate in any Matildas-related activities,'' Vivian said in a statement.

''The players feel they have been left with no option other than to take this course of action.''

The union is seeking an increase in wages, international match payments, improvements in accommodation, and other benefits for the women's team.

Matildas forward Ashleigh Sykes told Australian Broadcasting Corporation radio that the contract dispute was forcing players to choose between continuing their international careers or getting another job.

''Things are getting quite tight, they're (players) having to get credit cards and all that sort of thing ... to try and get through for the last two months and continuing into the future,'' she said. ''Who knows what's going to happen?''

''In my position at the moment it's been hard to get a job, but for me it's coming down to almost a choice now. Do I make myself available for Matildas duties, or do I work?''

The men's national team boycotted community events before a World Cup qualifier in Perth last week.

The PFA is also negotiating for more pay for domestic A-League players, and an increase in each of the 10 team's salary caps.

Gallop said that the Matildas' interests have been ''taken hostage'' by the PFA in the standoff over the interests of male professional players.

''Sadly, the Matildas will not be playing the USA because FFA and the A-League clubs can't meet the PFA's unaffordable demands in relation to the level of the salary cap for A-League players,'' said Gallop.