Britain's foreign office says transport hubs and fan zones might be targeted during Euro 2016 tournament.
Britain's foreign office has warned the Euro 2016 football tournament that will start in Paris on Friday is at risk of terrorism, pointing out that stadiums, transport hubs and fan zones "represent potential targets for terrorist attacks."
The foreign ministry said in a travel advisory that there will be a high threat of terrorism during the month-long tournament that will take place in stadiums across France.
"During Euro 2016, stadiums, fan zones, venues broadcasting the tournament and transport hubs and links represent potential targets for terrorist attacks," the statement read.
"You should be vigilant at all times, especially in areas hosting Euro 2016 events and follow the advice of local French authorities," it added.
The football tournament begins on June 10 and will run until July 10.
Ukraine on Monday said it had arrested a suspected far-right French terrorist who had a huge arsenal of weapons and was allegedly plotting an attack during Euro 2016.
A spokeswoman for Prime Minister David Cameron told reporters that the advice was a precautionary measure, not a result of specific intelligence.
"It is not in response to a new or specific threat ... It is in the context of making sure that the government and authorities are doing all they can to provide relevant information for fans," she said.
She also said security on trains to France and on Britain's borders will be further tightened.
Last week, the US made a similar warning to its citizens, saying not only French stadiums hosting matches but also crowded gathering points for fans might be targeted.