"This week we have sent back from the Narva border checkpoint 11 foreigners who are in Russia on the basis of a World Cup Fan ID but who do not have the right to enter Schengen territory," Indrek Püvi, head of the Border Guard Bureau of the Police and Border Guard Board's (PPA) East Prefecture, told BNS on Friday.

"Border guards on the southeastern border also caught three groups of illegal border crossers, altogether 17 people, early this week," he continued. "It is very likely that those people were also in Russia without a visa and on the basis of World Cup Fan IDs, but these circumstances will be determined in greater detail in the course of proceedings."

In recent weeks, in connection with the 2018 FIFA World Cup held in Russia, the PPA has caught several third country nationals attempting to gain access to the EU without a visa.

Under a simplified procedure, Russia allowed into the country and to some of the matches individuals with World Cup Fan IDs, which were to expire ten days after the end of the event. Russian President Vladimir Putin, however, announced on Sunday that Russia is to extend the validity of the Fan IDs through the end of 2018.

As a result, police in Estonia are calling on transport and logistics companies who travel between Estonia and Russia to remain vigilant and keep an eye on their vehicles whenever stopped to ensure that nobody has attempted to stow away in their vehicle.

"And if anyone sees anything, then we expect to be notified of this no later than at the border checkpoint," he added.