By Guillermo Parra-Bernal and Gustavo Bonato
SAO PAULO, June 9 (Reuters) - Subway workers went on strike in São Paulo for a fifth day on Monday even after a court ruled the stoppage illegal, spreading chaos across Brazil's biggest city just days ahead of the opening match of the World Cup soccer tournament.
The decision by subway workers, who seek a pay rise of almost twice the annual inflation rate, may trigger another day of record traffic jams in the city of over 20 million people.
Workers will vote on extending the strike at 1:00 p.m. local time (1600 GMT) following a downtown rally that will be joined by groups representing homeless workers.
Earlier on Monday, police used tear gas to break up the start of a demonstration blocking access to the Ana Rosa subway station in downtown São Paulo's southeastern corner. Workers burned waste bags in protest of the detentions of several subway union leaders. No injuries were reported.
"The World Cup is not an excuse for us" to strike, Paulo Pasin, president of Fenametro, the country's nationwide union of subway workers, told Reuters at Ana Rosa. "We want to reopen negotiations."
The World Cup kicks off Thursday as Brazil and Croatia face off at the Arena Corinthians stadium in São Paulo's north end.
Geraldo Alckmin, governor of the state of São Paulo, warned of massive dismissals following a labor court ruling Sunday that the strike is illegal. Workers lashed out at the ruling, fanning concern over potential clashes between police and strikers.
Analysts say São Paulo is gradually becoming a battlefield for dissenting political views, hampering the city's economy and creating a climate of unease ahead of the World Cup.
Frustration with broken promises and the ballooning cost of new World Cup stadiums contributed to widespread protests that drew over a million Brazilians into the streets during a warm-up tournament last year. This year, the largest demonstrations so far have been by homeless groups and striking workers using the backdrop of the World Cup to press their causes.
Workers want a 12 percent pay rise, with the state's subway company offering 8.7 percent. With major subway lines closed since Thursday, commuting in Brazil's largest city has been chaotic.
"This whole thing is making my life hell. Many times during the day I have to switch buses and vans. I have missed work - and I know am not the only one," Djalma Melo, who works as an office assistant, said near Ana Rosa station.
Police patrols were parked outside several other subway stations in São Paulo's west and southeast corners, with no incidents being reported. (Editing by Bernadette Baum)