Large cities across Iran are bracing for gridlock as the football-mad Islamic republic prepared to open its World Cup campaign against Mexico in Germany.

Iran supporter cheers as he watches the World Cup soccer match between Iran and Mexico on a huge video screen in Frankfurt June 11, 2006.[Reuters]

For the first time ever, Tehran's municipality has decided to show Iran's matches on giant screen televisions at major parks across the sprawling city. Police said they were anticipating huge crowds and traffic mayhem for Sunday's game.

"We recommend people stay at home to watch the match as much as is possible," Tehran's police spokesman, Mohammad Torang, told AFP.

"But if they want to watch the match on one Tehran's giant screens, we are ready to facilitate the traffic," he added, but nevertheless predicted that Tehran's streets would be brought to a "total standstill" if Iran managed to draw or win against Mexico.

If previous events are anything to go by, a good result is likely to prompt dancing on the streets and a cacaphony of firecrackers and horns well into the early hours of the morning.

"Having fun is the right of the people," Torang asserted, adding that police also shared the public's ambitions for the national team.

"Of course there will be some traffic restrictions in some of Tehran's main streets or squares, but all in all it will be to facilitate fun," he said.

President Mahmoud Ahmadinejad, however, will be watching the game on television in his office.

"The president will carry on working, but he will follow the game at the same time," a source in the president's office told AFP.

Iran's opening first-round match was kicking off in the southern German city of Nuremberg at 1600 GMT.