Portugal's telecom regulator has blocked an attempt by international operator Altice to buy control of local company Media Capital, saying it could create "significant obstacles" to competition.
The National Communications Authority, known as Anacom, said in a statement on its website Tuesday the deal needs to be reconfigured.
Netherlands-based Altice N.V., through its Portuguese telecoms company MEO, agreed in July to pay Spain's Prisa 440 million euros ($527 million) for its 94.7 percent stake in Media Capital.
Media Capital is one of Portugal's leading media groups, owning popular national television channels and radio stations.
The takeover was to be the latest addition to Altice's portfolio after expanding its telecommunications and cable presence in the United States and France.
The companies involved made no immediate comment.