The majority of Spain's top flight football teams have threatened to go on strike against a proposed new sports law which they argue benefits major clubs like Real Madrid and Barcelona.

La Liga -- which governs Spain's professional football divisions  -- has called an extraordinary assembly on Thursday to discuss next steps including a possible strike over the draft legislation which still needs the approval of parliament.

The row pits Real Madrid, FC Barcelona and Athletic de Bilbao along with the Spanish Football Federation (RFEF) -- the governing body of football in Spain --  against La Liga.

There are two main issues in the spat over the law which has the backing of Spain's ruling Socialists and the main opposition conservative Popular Party (PP).

One involves an agreement reached with private equity firm CVC which paid 2.0 billion euros in exchange for 8.2 percent of La Liga's revenues from its image rights during 50 years.

La Liga says the deal will give it a cash injection that will allow it to compete with the English Premier League but Real Madrid, Barcelona and Athletic Bilbao opposed it, saying it gives up too much for too little money.

La Liga wants the new sports law to shield this agreement. It believes the major clubs oppose it because it calls for a more equitable distribution of football revenues among clubs.

Big clubs want to "return to an old football model where there were huge inequalities and the growth of more modest clubs was greatly restricted," said the director general of second division side FC Granada, Alfredo Garcia.

The football federation, however, argues the agreement with CVC forgets modest amateur clubs and questions the legality of the deal.

"Now the government and the main opposition party are going to change the rules of the game and are going to  make legal what is illegal? That would be very serious," RFEF president Luis Rubiales told daily newspaper El Pais.

La Liga also wants the new sports law to make it possible  sanction clubs playing in competitions which it does not approve of, such as the proposed European Super League which would have been made up Europe's elite clubs.

Real Madrid president Florentino Perez was one of the main drivers of breakaway league.

In an advert published Tuesday in several Spanish newspapers on Tuesday, La Liga defended the need for a sports law "that does not favour the creation of a Super League that seriously damages Spanish football".

La Liga says the government had agreed to address its concerns in the new sports law but the amendments it called for ended up disappearing from the legislation.