By Brian Homewood
RIO DE JANEIRO, July 30 (Reuters) - Rioting Gremio supporters set fire to portable toilets, twice forcing their team's match away to arch-rivals Internacional to be interrupted on Sunday.
Play was halted as a thick plume of black smoke rose over the Beira-Rio stadium in Porto Alegre and firemen fought the blaze behind one of the goals.
The trouble broke out at halftime when the visiting Gremio fans threw around half a dozen plastic portable toilets into the moat which separates the field from the crowd and set them alight.
Television pictures showed policemen using fire extinguishers attempting to put out the blaze as play was stopped.
Although the game was re-started, the situation got worse as the smoke blew over the stadium and the referee ordered another stoppage shortly afterwards.
This time, the fire brigade arrived and brought the blaze under control despite being pelted with objects by the Gremio fans.
Gremio supporters continued dancing and celebrating on the terraces even as the smoke blew over them.
As the fire was put out, police fired teargas at the fans and brought the situation under control.
There was also trouble before the match as Gremio fans broke down part of a fence and invaded the area reserved for Internacional supporters.
Television pictures showed rival fans punching and kicking each other before truncheon-wielding riot police chased the Gremio fans back into their section.
The match itself ended in a drab goalless draw in which the teams shared 50 fouls.