Russian and Polish football fans were involved in a series of violent clashes ahead of Tuesday's Euro 2012 match between the two teams.
It is believed that at least 15 people have been injured, and more than 100 arrested, as a result of the clashes during a march mobilising thousands of Russian fans as a way of celebrating the country's national day.
Pictures have emerged of beatings and rival running battles between fans, while police reportedly fired warning shots in an effort to quell the violence.
SEE THE PHOTOS IN THE GALLERY ABOVE
A water cannon has been deployed around the city's fan-zone, although it is currently only being used as deterrent. However, formations of riot police are now patrolling central streets.
Some 6,000 policemen are on duty to prevent clashes from escalating, but they may not be enough as fans spread across Warsaw after the match.
The rivalry between the two countries has been intense for several years, and it was feared that tension could ignite in the build-up to the match as the two sets of fans entered the National Stadium, in Warsaw.
However, the two-kilometre march from the centre of Warsaw to the stadium was approved by local authorities, despite protests from the conservative Polish opposition.
Russia occupied Poland for more than a century and held control over the country after World War II, until 1989.
Violence had been anticipated in the days leading up to the match.
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