WASHINGTON (Reuters) - The NFL was on the verge of its first work stoppage in almost a quarter of a century when negotiations over a new labor deal collapsed on Friday.

The last real hope for a quick end to the dispute ended when the union representing the players (NFLPA) filed a court application to dissolve itself after failing to agree with the league and team owners.

The NFLPA's decision to decertify means the players were no longer covered by a collective bargaining agreement and were free to take individual legal action against the NFL.

"We informed the owners that significant differences remained," NFLPA executive director DeMaurice Smith told reporters in Washington before the union applied to decertify.

The NFL was expected to impose a lockout, the first work stoppage in America's most popular professional sport since 1987, some time after the current agreement expires at 11:59 p.m. Friday.

"As you know the union walked away from mediation process today to decertify," NFL Commissioner Roger Goodell said. "We don't believe that mediation is the fairest and fastest way to reach an agreement that works for the players and the clubs."

Both sides said they were unable to reach an agreement over a whole range of issues, including how to split more than $9 billion in annual revenue. Other issues include an increase in the regular season schedule to 18 games from 16, a rookie wage scale and pensions for former players.

They twice extended negotiations in the hope of finding a compromise but the federal mediator who oversaw the 17 days of talks said it was clear they were no closer to a resolution.

"It is (my) considered judgment ... that no constructive purpose would be served by requesting the parties continue mediation at this time," said federal mediator George Cohen.

Under the current agreement, owners received a guaranteed $1 billion of annual revenue, which totaled around $9 billion. The remaining money was split, with the players getting around 60 percent and the owners 40 percent.

The league and owners want to increase their automatic cut by another $1 billion, arguing that operational costs had risen since the last deal was struck five years ago.

But the players wanted to maintain the status quo, claiming the owners had failed to provide them with enough financial evidence to prove they needed a bigger slice of the profits.

"Not once have the players asked for more money during this negotiation. That is a fact," New Orleans Saints quarterback Drew Brees said in a statement released on Twitter.

"Past players sacrificed a great deal to give us what we have now in the NFL, and we will not lay down for a second to give that up.

"I don't expect anyone to feel sorry for us. We have a responsibility and at some point you just have to stand up for what is right."

(Reporting by Julian Linden in New York; Editing by Frank Pingue)