Polls have opened in Spain's wealthy northeastern region of Catalonia to choose 135 regional parliamentary seats.

The Sunday election is viewed as a possible referendum on Catalonia's independence from Spain.

Incumbent regional president and pro-independence candidate Artur Mas told members of his Convergence and Union Party last week that independence is within sight. If he wins, Mas has pledged to hold a referendum asking Catalans if they wish to split from Spain.

But Citizens Party presidential candidate Albert Rivera says Catalonia would not benefit from splitting away from Spain.

Political experts expect Mas will win, but no one is predicting Catalonia's secession from Spain.

The Mas government called early elections as part of a power struggle with the central government run by Prime Minister Mariano Rajoy.