"The league's council of [club] presidents approved an expansion of the competition to 18 clubs in the 2012/13 season," the LPFP said in a statement late on Monday.
The expansion would be achieved by allowing the bottom two teams this season to avoid relegation.
The decision, which provoked a heated exchange between club delegates, still needs to be ratified by the Portuguese Football Federation and Portugal's National Sports Council. Some of the clubs which voted against the proposal said they would challenge the measure.
"This was an historic day, we managed to gather support for a structural question and an eventual complaint to end the monopoly of TV rights," Figueiredo said.
This means that in Portugal, as well as in neighboring Spain, the bulk of broadcast rights revenues are dominated by bigger clubs, with half of the revenues going to the so-called "big three" of Benfica, Sporting and Porto.
