Organisers of a float in Brazil's Carnival parade have caused controversy after naming a seven-year-old to front their group as a drum corps queen.

A judge is considering blocking Julia Lira's participation in next week's parade and a state agency that defends children's rights says she is too young to take on a traditionally sexy role.

But the girl's father, who happens to be the president of the samba group, says Julia is a natural who can easily samba through the 80-minute parade route in Rio's sweltering summer heat.