The Catalan referendum had taken place "in an illegal context" and therefore it is "completely unprecedented," Russel Foster said in an interview with Radio Sputnik.
The expert compared the Catalan vote with the referendum on Brexit and came to a conclusion that the events are completely different in their nature.
"We have to remember that while the European Union was unhappy with the Brexit vote, Brexit went to a formal, legal proceeding. Everyone knew that the referendum was going to take place and all factions agreed that they would respect the outcome of the referendum…. The Catalan referendum had taken place outside of Spanish law," the expert said.
"What also makes it a bigger threat, is that with Brexit we have the same country that joined the European Union in 1973. But with the Catalan vote, there is a desire for a completely new country which never joined the EU to withdraw from it," Foster added.
Catalonia is one of the most economically powerful regions in Spain, and its possible secession "would create a serious economic and financial crisis for the
Spanish state in addition to all political and constitutional problems," the expert believes.
According to the analyst, the consequences of such a scenario would be "nothing less than catastrophic" and lead to "a crisis that Europe has not seen since WWII."
"Since 1955 the mantra has been: more Europe, more integration. And the only way to deal with the emerging problems — especially in this century of globalization, climate change, terrorism, migration — is for countries to cooperate and form large regional powers," Foster said.
According to him, if Catalonia breaks away, this will be a symbolic statement of a return to ethnic nationalism and small nation-states, which are totally incapable of dealing with the problems of the 21st century.
"So, Catalonia's independence will be a disaster for Spain, a disaster for Europe and, particularly, for the Catalonian people," the expert concluded.
On Sunday, Catalonia held an independence referendum, in which around 90 percent of the voters supported the secession from Spain. While Catalan authorities claim the plebiscite was valid, Madrid refuses to recognize the vote and hold negotiations with the region.