Updated

The start of the annual San Fermin bull-running festival has been delayed briefly after suspected Basque nationalists obstructed the view in a historic city plaza before dignitaries could set off a firework marking the beginning of reveries.

The nine-day fiesta featuring a heady mix of alcohol, bulls and adrenaline began some 20 minutes later than planned on Saturday after organizers removed an oversize Basque flag that blocked the balcony from where the rocket, known as Chupinazo, was to be ignited.

Thousands of revelers, dressed in white, packed the square chanting "Viva San Fermin" and waited 19 minutes as the flag was removed.

Immortalized in Ernest Hemingway's 1926 novel "The Sun Also Rises," the ancient festival is famous for daily bull runs and all-night partying.