By Zjan Shirinian

The strike has left a city used to traffic jams facing some of the worst it has seen ©AFP/Getty ImagesMetro workers in São Paulo have voted to stay on strike indefinitely, plunging the opening FIFA World Cup game in the city on Thursday into potential chaos.

Traffic jams have crippled roads throughout São Paulo since Thursday (June 5), when most metro stations closed as workers chose to stay away in a row over pay.

They are demanding a pay rise of 12.2 per cent, but the company which employs them is offering 8.7 per cent.

A labour court ruled at the weekend that unions had abused their powers in calling the strike, and the metro company had acted "in good faith".

But hours later, the unions held a ballot for continued strike action, which was backed.

They say the strike will be called off if pay demands are met.

Meanwhile, police have this morning used tear gas to disperse crowds in a protest called by metro workers.

Around 300 people, reportedly centred around Ana Rosa station in the centre of São Paulo, were met by riot police.

Rubbish has been set of fire in an attempt by protesters to block a street.

"It is not our intention to continue the strike into the World Cup," Altino Prazeres, president of the metro workers' union, told Brazilian newspaper O Globo.

"Our intention is to solve the problem.

"But that should be the Government's aim too."

The Se metro station in São Paulo is deserted as workers continue their strike over pay, which could now disrupt the start of the World Cup ©AFP/Getty ImagesThe Se metro station in São Paulo is deserted as workers continue their strike over pay, which could now disrupt the start of the World Cup ©AFP/Getty Images

Brazil are due to face Croatia in the opening game of the World Cup at the Arena Corinthians on Thursday (June 12) at 5pm Brasilia time.

The stadium is on the outskirts of São Paulo, meaning travelling to the venue without public transport will be a challenge.

Traffic chaos seen on Thursday and Friday was unusual even by the city's standards.

There were reportedly more than 200 kilometres of traffic jams across the city in the morning rush hour on both Thursday and Friday.

The Arena Corinthians is due to host three other group games during the World Cup, with Uruguay playing England on June 19, 2010 runners-up The Netherlands facing Chile on June 23, and South Korea against Belgium on June 26.

It  is also scheduled to play host to a round of 16 clash on July 1, and one of the two semi-finals on June 9.

São Paulo State Governor Geraldo Alckmin has said he will dismiss employees who do not come to work today.

The build-up to the World Cup has not been immune to problems.

Football's governing body FIFA and the Local Organising Committee only received the 12 stadiums being used for the tournament at the end of last month, and continued protests in cities across Brazil - some against the staging of the World Cup - have left questions over what impact, if any, they will have on it.

The Brazilian Government has launched its largest mobilisation of armed forces, using 30,000 military personnel to patrol its entire 17,000-kilometre national border ahead of the World Cup, the first to be staged in Brazil since 1950.

It is due to run until July 13, with the final at Rio de Janeiro's Maracanã.