Hundreds of Catalans have left yellow roses at a central Barcelona square in support of jailed separatists they view as political prisoners in their campaign to break away from Spain.

It gives a political overtone to Monday's celebration of "Sant Jordi," the patron saint of the Catalan region, known in English as St. George. The festivity also coincides with World Book Day.

Legend has it that the saint killed a deadly dragon and a red rose appeared from its flesh. So Catalans give a book and a red rose as gifts to mark the day.

But amid Catalonia's struggle for independence, many have chosen yellow roses instead, a color that symbolizes the secessionist movement.