SCOTLAND'S referendum on independence is being cited as an "enlightening example to Spain" in a row over a ruling that made Catalonia's declaration of sovereignty null and void.

Leading Spanish politicians have called for the north-eastern Spanish region to be treated like Scotland in a protest to European Parliament president Martin Schulz, after the Constitutional Court of Spain suspended the province's declaration of sovereignty.

The decision made last week means the court will consider an appeal by the central government against the declaration on the grounds it was unlawful.

The declaration, approved by the region's parliament in January, described the 7.5 million Catalan people as "politically and legally sovereign" and nationalists saw it as a first, symbolic step towards independence.

The battle over sovereignty could lead to a major change to the identity of Spain, as the Catalonia position is being closely watched by those supporting the independence of the Basque region of northern Spain.

A group of six key Spanish MEPs led by Izaskun Bilbao, the first female president of the Basque Parliament, has lodged a protest with the European Parliament president that the move created a "bad democratic precedent" by contrast to Scotland's independence claim.

In a letter signed by the six, they state: "The respectful behaviour of Prime Minister Cameron and the British Government with the will of Scotland to celebrate an independence referendum sends an enlightening example to Spain."

The Catalan Government plans to hold a referendum on independence in 2014.