Fitch said Thursday that the political tensions between the central government and Catalonia "are likely to worsen over the short term," leading to unforeseeable events, including a potential disruption of the state liquidity funds to Catalonia.

As a result the agency put Catalonia on a 'rating watch negative' footing, meaning it could downgrade from its current BB level, which is already in the "speculative" or junk territory.

However, it added in a statement that it expected the current tensions between Madrid and the Catalan authorities to ease. "In the medium term, our central assumption remains that current tensions will ease, and that there will be a continuation of the ongoing support of the central government to Catalonia for its debt servicing." 

Read more: Spain's Consitutional Court suspends Catalan independence parliamentary session

Late Wednesday, Standard and Poor's (S&P) Global Ratings placed its ratings for Catalonia "on CreditWatch with negative implications," saying that the Catalan government's political confrontation with Spain's central government had escalated in view of a planned Catalan declaration of independence as early as Monday.

"We see a risk that this escalation may damage the coordination and communication between the two governments, which is essential to Catalonia's ability to service its debt on time and in full," the S&P statement continued.

Currently, S&P rates Catalonia's debt at B+ and B. The agency also expressed the hope that it could "resolve" the CreditWatch within the next three months, if the tensions between Madrid and Barcelona ease.

Read more: Catalan banks prepare for shifting headquarters after secession

In Spain's worst political crisis in decades, images of police beating unarmed Catalans taking part in the vote on Sunday sparked global concern. Catalonia is a major engine for Spanish growth, and accounts for around 19 percent of its GDP.

uhe/tr (Reuters, AFP)