Thousands of protesters have marched across Spanish cities to decry tough austerity measures as the protest movement gains momentum, with signs it could culminate in a general strike in November. Sunday's march is the latest in a series of protests staged by hundreds of thousands of Spaniards almost on a daily basis over the past few months. The protests have presented the centre-right government with a headache as it is due to hold regional elections. Al Jazeera's Paul Brennan reports from Madrid.