Spain's government has passed a law making it easier for companies to move their official base out of Catalonia, a move that could deal a heavy blow to the region's finances.

According to unconfirmed reports, the decree was designed specifically for Spanish lender Caixabank, since it makes it possible for the bank to transfer its legal and tax base out of the region without holding a shareholders' meeting, as stated in its statutes. Caixabank's board is due to meet on Friday to discuss the issue.

At least half a dozen companies, including the fifth-largest lender, Banco Sabadell, have already relocated or agreed to do so.

Economy Minister Luis de Guindos said: “This is the result of an irresponsible policy that is causing uneasiness in the business community.”

Spain's main stock index is down slightly, with Catalan banks leading losses amid uncertainty over the region's independence bid.

The Ibex 35 index lost 0.9 per cent to 10.126 points in Madrid by midday on Friday.

The biggest fallers were Banco Sabadell, the country's fifth-largest bank by assets, and Caixabank, Spain's third-largest.

Catalonia referendum protests – in pictures Show all 10 1 /10 Catalonia referendum protests – in pictures Catalonia referendum protests – in pictures Demonstrators block a Guardia Civil vehicle as they try to leave the Department of External Affairs, Institutional Relations and Transparency of the Catalan Government office in Barcelona AP/Emilio Morenatti Catalonia referendum protests – in pictures Demonstrators react as they try to stop the car carrying Xavier Puig, a senior at the Department of External Affairs, Institutional Relations and Transparency of the Catalan Government office, after he was arrested by Guardia Civil officers in Barcelona AP/Emilio Morenatti Catalonia referendum protests – in pictures A demonstrator reacts as he tries with others to stop the car carrying Xavier Puig, a senior at the Department of External Affairs, Institutional Relations and Transparency of the Catalan Government office, after he was arrested by Guardia Civil officers in Barcelona AP/Emilio Morenatti Catalonia referendum protests – in pictures Spokeswoman of the Catalan pro-independence anticapitalist party "Candidatura d'Unitat Popular - CUP" (Popular Unity Candidacy), Ana Gabriel, talks to the media in Barcelona Josep Lago/AFP Catalonia referendum protests – in pictures Republican Left of Catalonia party's (ERC) Member of Parliament Joan Tarda (C) attends a demonstration outside the regional Economy Ministry in Catalonia during a police search for documents connected with the organisation of the Catalan independence referendum, in Barcelona EPA/Alejandro Garcia Catalonia referendum protests – in pictures A man holds pro-referendum poster next to a Spanish Civil Guard who stands in front of the Economy headquarters of Catalonia's regional government in Barcelona. The operation comes amid mounting tensions as Catalan leaders press ahead with preparations for an independence referendum on October 1 despite Madrid's ban and a court ruling deeming it illegal Josep Lago/AFP Catalonia referendum protests – in pictures People hold placards reading "Democracy" as they protest in front of the Economy headquarters of Catalonia's regional government in Barcelona AFP Catalonia referendum protests – in pictures A crowd of protesters gather outside the Catalan region's economy ministry after junior economy minister Josep Maria Jove was arrested by Spanish police during a raid on several government offices, in Barcelona Reuters/Albert Gea Catalonia referendum protests – in pictures People holding 'Esteladas' (Catalan pro-independence flags) attend a protest near the Economy headquarters of Catalonia's regional government Lluis Gene/AFP Catalonia referendum protests – in pictures People demonstrate on a Spanish Civil Guard Police car outside the Catalan Vice-President and Economy office as police officers holds a searching operation inside David Ramos/Getty Images

Two Catalan companies, textiles maker Dogi and reprographics company Service Point Solutions, saw their shares surge after they said they had plans to relocate.

Cava-maker Freixenet, a household name, is also considering a move while telecommunications provider Eurona and biotech firm Oryzon have already completed their relocations.