Spanish Prime Minister Mariano Rajoy on Wednesday dismissed Catalonia's non-binding vote on secession from Spain as a failure, and prosecutors were considering legal action against Catalan officials for conducting the ballot.

Rajoy said that in addition to being illegal, few Catalans voted on Sunday, despite months of pro-independence campaigning by authorities.

"Two out of every three Catalans didn*t bother taking part," said Rajoy. "The pro-independence plan was for it to be a show of strength and (instead) it has shown us its weakness."

Catalan officials say that out of 6.3 million potential voters, 2.3 million cast ballots, with 80 percent of them approving secession. The 6.3 million total included 1 million immigrant residents and citizens aged 16 and 17, who normally would not be on the region's electoral census.

Catalan regional President Artur Mas nevertheless claimed the poll was a success, and on Tuesday he demanded talks with Rajoy about a possible official independence referendum similar to the one held in Scotland in September. The "no" voters won that referendum.

Rajoy said he was open to dialogue but rejected having a preset outcome and opposed any interference with national sovereignty. He urged the Catalan government to accept reality and begin ruling for all Catalans, not just those who favor independence.

The non-binding referendum was held even though Spain's top Constitutional Court called for its suspension while considering the government's claim that it would be unconstitutional.

Prosecutors who are independent of the government are now studying possible legal action against Mas and other Catalan officials for having gone ahead with the vote, even though it was presented as non-binding.

Angry at Spain's refusal to give their wealthy region more autonomy, Catalan politicians have been pushing for an independence vote for two years.