BREAKING: @TheMatildas withdraw from their Sydney-based camp ahead of their USA tour after failed negotiations with FFA this afternoon. — Lucy Zelic (@LucyZelic) September 8, 2015

The strike casts serious doubt over the Matildas' USA tour, where they are scheduled to play two fixtures against the USA women's national team on 18 and 21 September (AEST).

PFA Chief Executive Adam Vivian confirmed the players’ decision to not attend the camp after further talks with FFA failed to secure a new collective bargaining agreement (CBA).

“This decision has not been taken lightly, however the players feel they have been left with little option as the current proposal is simply unacceptable,” Vivian said.

A PFA statement read: Following the expiration of the Matildas CBA, the players are under no contractual obligation to undertake any Matildas related activities.

“FFA has failed to recognise the significant sacrifices the Matildas players are forced to make in playing for their country. Their proposal would see players continue to be:

:: unfairly remunerated for the work they undertake;

:: denied access to a high performance environment, which dramatically reduces their ability to compete with the world’s best; and

:: restricted in their ability to grow the women’s game.

Matildas goalkeeper Lydia Williams said the players stood united in this latest action, which comes on the back of the Socceroos' decision to last week to forego all commercial obligations while in Perth for the 2018 FIFA World Cup qualifier against Bangladesh.

“This was an extremely difficult decision to make,” Williams said. “However it’s simply unfair to continue to expect us to make enormous sacrifices to play for Australia.

“This is about the future of Australian football. We want to establish football as the sport of choice for Australian women, and we want to be one of the best nations in the world.

“FFA’s stance indicates that they do not share these ambitions, nor do they understand and respect what we have given to the game. We are simply asking FFA do their bit so we can grow the game together.”