Provocative hip-hop star M.I.A. is taking on the might of America's National Football League 18 months after executives began legal proceedings against her for a rude gesture she made during her performance with Madonna at the 2012 Super Bowl.

The Paper Planes hitmaker upset Nfl bosses when she flipped her middle finger at the camera during the show, and they demanded she pay $1.5 million (£1 million) for breaching her performance contract.

According to The Hollywood Reporter, the Nfl chiefs began taking legal action in March, 2012, filing papers at the American Arbitration Association, accusing M.I.A. of "a flagrant disregard for the values that form the cornerstone of the Nfl brand and the Super Bowl."

They pointed out that the star had agreed to "acknowledge the great value of the goodwill associated with the Nfl and the tremendous public respect and reputation for wholesomeness enjoyed by the Nfl" and "ensure that all elements of (her) performance... shall be consistent with such goodwill and reputation."

M.I.A. is now fighting back, insisting it is "ridiculous" for the Nfl executives and sports fans offended by her middle finger salute to "devote such furor to this incident while ignoring the genocide occurring in her home country (Sri Lanka) and several other countries."

Her lawyer, Howard King, says, "The Nfl's claimed reputation for wholesomeness is hilarious in light of the weekly felonies committed by its stars, the bounties placed by coaches on opposing players, the homophobic and racist comments uttered by its players, the complete disregard for the health of players and the premature deaths that have resulted from same, and the raping of public entities ready to sacrifice public funds to attract teams."

And M.I.A. and her legal rep are asking fans to help them make a case against the Nfl.

King adds, "We encourage people to submit their examples of how the actions of the Nfl, its stars, coaches, advertisers, broadcasters, team doctors and owners have damaged or destroyed any vestiges of any reputation for wholesomeness ever enjoyed by the Nfl. These submissions, which we plan to use to bolster M.I.A's defense, will help balance the playing field, as they very well could eliminate the burden of undertaking a formal survey of the history of unwholesome behaviour.

"We are planning an all-out assault on the Nfl's claims of being a brand devoted to high morals."