A group of England football supporters were reported to have been injured in an attack by Ukraine fans in Kiev ahead of a World Cup qualifier.
Three Britons were taken to hospital in a clash between England supporters and fans of the home team. Witnesses said that the Ukrainian men attacked the English fans with knives outside a coffee shop in the capital.
The fight broke out after the two sides traded insults, police said.
A Foreign Office spokesman said: "We are aware of incidents in Kiev involving British nationals. We are providing consular assistance."
According to reports, one of the fans was stabbed. Others suffering a head injury and severe bruising. No arrests have been made.
It is understood that two of the victims have since been released from hospital. A third has been kept in for observation.
Rachel Barber, head of the UK police delegation in Ukraine, said: "We are aware of what happened last night and we will be going round most of the major bars, including this particular one, to make sure there are no problems.
"We would urge supporters to enjoy themselves but to do so without upsetting anybody."
England are due to play Ukraine in Kiev's Olympic stadium on 10 September. They top Group H with 15 points, ahead of Montenegro on goal difference.