Catalan officials say at least 337 people have been injured in clashes as police try to prevent voting in Catalonia's independence referendum, the BBC reported on Sunday.

The Spanish government has pledged to stop a poll that was declared illegal by the country's constitutional court.

Police officers are preventing people from voting, and seizing ballot papers and boxes at polling stations.

In the regional capital Barcelona, police used batons and fired rubber bullets during pro-referendum protests.

The latest injury toll was confirmed by a spokesman for the Catalan regional government, as well as the region's health department.

Separately, the Spanish interior ministry said 11 police officers had been hurt.