The upcoming EU referendum in the U.K. will be carefully monitored within the Spanish region of Catalonia, according to its president, who told CNBC that it will monitor any reaction and digest what that could mean for Catalonia's own separatist ambitions.

"The British people have the right to decide have the right to decide whether or not they want to be part of the EU," Carles Puigdemont told CNBC on Thursday.

"And I shouldn't interfere in this. I express Catalonia's wish of being in the EU. We'll see what happens. But I notice a paradox: the EU makes huge efforts to avoid the U.K. leaving while it threatens Catalonia with kicking us out if we declare ourselves independent."

Puigdemont became the president of Catalonia, a prosperous region in northeastern Spain that has a long history of pro-independence sentiment, in January, succeeding independence figure Artur Mas in the role.

Politics in the region involves a mix of differing views on EU membership. A "Junta pel Sí" (Together for Yes) group is a coalition of center-right and center-left parties (including Puigdemont's Democratic Convergence of Catalonia (CDC) party). Crucially they want the prosperous region to stay in the EU. However, other parties such as the far-left Popular Unity Candidacy (CUP) do not. Nonetheless, all parties campaign in favor of Catalan independence and a "sustainable and peaceful" separation from Spain.

When Puigdemont took up the role of president, he pledged to start the process of setting up an independent Catalan state but that drew anger from other quarters in Spain, not least of all with the Madrid-based government itself with Prime Minister Mariano Rajoy calling the plans to secede Spain a "provocation."

For its part, the EU has said that it should not be taken for granted that an independent Catalonia could even stay in the EU as It does not want to set a precedent for other separatist movements in Europe.

"To be honest, I am very worried about the possibility of the U.K. leaving the EU. But of course, like in the case of Catalonia, we have to respect the right to decide of the British people on a relationship that part of the Brits consider is not satisfying enough. We will see what happens."

He noted that, certainly for Europe, a "Brexit" would be "an important loss."

"I don't know enough about the internal situation of the U.K. to know what exact impact it would have, but it would also be serious. But without a doubt for Europe it would be very bad news if the U.K. leaves. But I insist, even if the decision of the British people is to leave the union, it will be in everybody's interest to reach an agreement that in practice can put in action a better relationship for both and lose what the U.K. considers the bad aspects of the relationship. I hope in practice we will be able to find a balance whatever the decision is."