Rio de Janeiro, Feb 5 (IANS): South American football's governing body Conmebol has opened an investigation into the stadium collapse in southern Brazil that injured seven fans last Wednesday.

Five people were taken to hospital after the fencing collapsed during a stampede in Gremio's home Copa Libertadores' match against Ecuador's Liga de Quito at Gremio Arena in Porto Alegre, reports Xinhua.

Gremio won the match 5-4 on penalties to advance to the tournament's group stage.

"Conmebol's disciplinary unit has initiated a process against Gremio, notifying the club to present its arguments about what happened," Conmebol's disciplinary tribunal chief Adrian Leiza said Monday.

Among the sanctions facing Gremio is a hefty fine, the relocation of a home match to a neutral venue or a home game behind closed doors. Gremio's first Libertadores group match is against Chile's Huachipato Feb 14, scheduled to be played at Gremio Arena. The club's lawyer Gabriel Vieira denied Conmebol had already laid charges over the incident.

"There is the risk of punishment but we haven't received any formal notification. We are going to defend our case," Vieira said.

All the five fans taken to hospital have been released having suffered only minor injuries. The crush occurred when supporters in an unseated area of the stadium celebrated a goal by performing an 'avalanche' causing fencing to collapse and dozens of people to fall onto the venue's playing surface.

Brazil's football confederation (CBF) chief Jose Maria Marin admitted Thursday the incident had highlighted the need for Brazil to improve health and safety standards ahead of next year's FIFA World Cup.