The Portuguese government said this week it planned to file a formal complaint with the European Union about the Spanish nuclear waste plant, which the Spanish government has authorised to be built in Almaraz, 100 kilometres from the Portuguese border. The Spanish authorities did not consult with the Portuguese authorities before green lighting the project.

Speaking to journalists in Lisbon, Augusto Santos Silva said there had been "several days of diplomatic work,” to establish whether “the meeting set for 12 January [in Madrid] will be a useful meeting."

"Obviously, if it is a useful meeting, Portugal will take part in it,” he said.

"It would not be useful to have a meeting about decisions that have already been made. It would be useful to have a meeting in which the ministers can discuss their arguments face-to-face, their reasoning, procedures to be adopted, the remedial measures, if there are any,” he added.