US football fans, who have bought more World Cup tickets than every nation other than hosts Russia, have been warned about travelling to this summer’s event.

The US has not qualified for the tournament, but with 16,642 tickets bought, American fans were the biggest foreign buyers out of almost 400,000 tickets sold in the most recent sales period.

Relations between Russia and Western nations have deteriorated of late, and particularly since the poisoning of former Russian spy Sergei Skripal in the UK last month.

“We won’t have the same ability to protect our citizens or even just deal with the regular consular affairs,” The Daily Telegraph quoted an unnamed senior US administration official as saying.

He said they should “think twice” about travelling to Russia.

The Russian Embassy in Washington responded to the claims by saying all tourists would be welcome.

“Despite the active anti-Russia campaign in the leading American media, and maybe because of it, the interest for our country is growing,” it added. “Welcome to Russia, Americans!”

Meanwhile, the Croatian football federation has told fans that all of their World Cup games are now sold out.

Croatia are in Group D with Argentina, Nigeria and Iceland.

“All tickets for Croatia’s group matches in Russia have been sold. Stadiums in Kaliningrad, Nizhny Novgorod and Rostov are all sold out, all sections,” Nikša Martinac, who is in charge of ticketing at the Croatian football federation, told Jutarnji List.

“For not even one of the three matches were there tickets available in the second round of ticket sales. The Argentina match was the first to sell out.”

IMAGE: U.S. Department of State