In comments to journalists after a visit to a victim support association in Lisbon, the president thus sought to play down the debate triggered by the joint announcement made by the leaders of France, Germany, Spain and Italy after a summit of the post-Brexit 'big four' that they favoured a multi-speed EU, in which some member states can move forward faster than others.

"A multi-speed Europe already exists and we, fortunately, belong to the first speed, in the euro," the president said. "There are those that do not belong to the euro, there are those that do not belong to other [forms of] reinforced cooperation.

"It already exists, it's not new at all," he said.

According to de Sousa, "Portugal, and this is a good thing, is always in the front line, because it's in the euro, it supports common positions and policies in the matter of refugees and migrations, it supports greater political integration in the European Union, and it takes the view that it is fundamental to reinforce the ties between the European Union and NATO."

"The fundamental thing is that in those speeds Portugal is always, as [previous] President [Aníbal] Cavaco Silva, in the pack at the front, [or] as the prime minister António Costa now says, in the front rank," de Sousa said. "Basically, I don't know if you understand that they're different expressions to say the same thing. We must be in the pack at the front, in the front rank."

De Sousa noted that "there are other countries that want to be in the second rank, in a second group", adding that "they have a right to that, so long as the first speed is open amd, when they change their mind, or could or want to change their mind, they can join those that are in the first rank."

Asked whether Portugal had the capacity to stay "in the front rank", de Sousa said that he was "determinedly optimistic" on that, based on what the country had achieved so far.

There is no prospect, he added, of Portugal leaving the EU, or the euro, which he said "had and has and will have many more advantages for Portugal than not belonging" to it.