“In my opinion, it is highly probable that at least two member states, maybe more, will vote no," said Ruairi Quinn, who headed up the EU's Economic and Financial Affairs Council in 1996 and helped lay the groundwork for the introduction of the single currency.
"Spain will not want to create the precedent in another member state of a nation/region deciding to leave and join the EU in their own right," the politician added in a statement put out by the anti-independence for Scotland movement Better Together.
“Such a political development would really encourage Catalonia and the Basque Country to agitate for secession from Spain," the statement continued.
Spain has previously said it would give full consideration to the entry of an independent Scotland into the EU as long the country's secession process was legal.
But Barcelona-based journalist and EU expert Carme Colomina agreed with Quinn's analysis.
"I don't think Spain would want to see an independent Scotland within the EU as it would set a dangerous precedent for Catalonia," Colomina told The Local.
"But I also believe that if Catalonia does become an independent state, the EU would take a pragmatic approach and decide at that stage if it was in the EU's interest to accept Catalonia.
"The EU always acts in its own interests," she added.
Colomina was keen to stress that the political processes in Catalonia and Scotland weren't really comparable: "In Scotland we have seen a political party push for a vote on independence, while in Catalonia the regional government has been 'dragged along' by the will of the people," she said.
She also said the two cases were different because leaders in Scotland had been in open dialogue with the central government while the Spanish government had refused to conduct similar negotiations with Catalonia.
"In the end, the EU is more likely to accept Catalonia as an independent nation if there has been a negotiated agreement with Spain," Colomina added.
The EU has previously stated that Catalonia would automatically be kicked out of the 28-country group if it voted in favour of independence, and would then have to reapply for membership.
"What is more important at this stage, however, is not the issue of whether the EU would to accept a Catalan state. The key question is how to legally recognize the will of the people in Catalonia on independence," Colomina argued.
The leaders of the Spanish region of Catalonia are planning to stage a November 9th poll on whether to split from the rest of Spain. Madrid has labelled the vote illegal, but regional president Artur Mas has vowed the vote will go ahead.
Colomina believes the vote is now absolutely crucial.
"There are no other counter offers to the (November 9th) referendum at this stage. There is no alternative so the vote has become critical. The issue won't go away."
Support for independence in Catalonia was about 45 percent in April, according to the regional government's most recent polling.
Scotland will go to the polls on September 18th to vote on independence from the United Kingdom. A YouGov poll run by the UK's Times newspaper put support for independence at 43 percent.