Reports in the Spanish press say La Sexta will file legal papers against Zattoo in September. Teecino, TVE, Antena 3 and Cuatro are deciding exactly what action to take.
Spanish law permits cable channels to broadcast the analogue TV channels as long as broadcasters have negotiated a financial agreement to do so. Zattoo is said not to have entered into any agreements, although its directors claim they are operating legally.
BBC World has also accused Zattoo of using its logo without permission.
Zattoo makes its money through a system that shows a brief ad to viewers every time they switch channels.