Two Brazilian football fans were shot dead Sunday as violence marred an official test event for a 2014 World Cup stadium.

According to local judge Maria Jose Bentes, more than 200 people were arrested in the northeastern city of Fortaleza over a series of incidents in the vicinity of the Castelao Stadium.

Military police said the fatal shootings occurred during a confrontation between rival fans before the Ceara-Fortaleza match, which officially opened the venue.

Two Ceara supporters were shot in the head and died at the scene, within four kilometres of the stadium. One of the victims was identified as 30-year-old Glauber de Souza Damesceno.

A Fortaleza supporter has been arrested for suspected double homicide.

In a separate incident also before the match, a homemade grenade was let off at the city's Lagoa bus terminal by members of the Uniformed Fortaleza Fan Club, Globo reported.

"The bomb was inside a snooker ball and contained several steel nails," a policeman told local media. "Fortunately nobody was hurt."

The Castelao Stadium will be one of six venues used during June's Confederations Cup and will also host matches at next year's World Cup.

Sunday's incidents are the latest in a series of violent episodes involving Brazilian football fans.

In August last year, 29-year-old Diego Martins was shot dead before a Brazilian championship match between Rio de Janeiro rivals Vasco da Gama and Flamengo.

And in February this year, 14-year-old Kevin Beltran Espada was killed by a flare allegedly let off by a Corinthians supporter during a Copa Libertadores match in Bolivia.

Twelve fans of the Brazilian club remain in custody in the city of Oruro, two of whom who have been charged with homicide.