The Swiss Footballers' Union (SAFP), describing the situation as unacceptable, also claimed that players at the club had still not been paid their wages for November and December.
Neuchatel, where new owner Bulat Chagaev fired four coaches in his first four months after taking over in May, had already been docked four points in December, a decision which the club has appealed.
The latest sanction was imposed due to failure to pay social security contributions in October.
The Swiss football league's website reported that captain Stephane Besle (pictured), Javier Arizmendi, Vincent Bikana and Haris Seferovic had been fired on Wednesday.
"It's painful for the Xamax adventure to end this way," said Frenchman Besle, who had been at the club for six seasons.
"I wasn't prepared to find myself on the transfer market again so quickly."
Seferovic was in the Switzerland team which won the World Under-17 Championships in 2009.
SAFP President Lucien Valloni said the players had been dismissed "without plausible motives" while the squad was owed two months' wages.
"The SAFP has established that the players' wages for November and December 2011 have not been paid," he said.
"These circumstances could no longer be accepted by the players' union. The manner and way in which players have been treated is a sign of lack of respect."
"It's clear that all the players in this situation are in the right."
Nobody at the club was available to comment.
Chagaev, a businessman who hails from Chechnya, bought the club in May saying that he wanted to take Neuchatel into the Champions League.
During the summer, he sacked the club's administrative staff and ended all the sponsorship contracts.
They began the new season with 3-0 home defeat by FC Lucerne, prompting the club to fire Brazilian goalkeeper Rodrigo Gallato after one game.
In November, Neuchatel survived a request for bankruptcy made by a players' agent who took the club to court alleging that he was owed 400,000 Swiss francs ($424,000).
However, since then, public prosecutors have opened another case alleging that Chagaev had falsified a letter from a bank he used during a hearing.
