England had their biggest following of the World Cup against Croatia in Moscow
Chants of a "possible discriminatory" nature by England fans during their World Cup semi-final defeat by Croatia, are being investigated by Fifa.
It relates to the chanting of "no surrender" by England fans and other potentially discriminatory songs.
"We can confirm that a report has been filed in relation to chants of a possible discriminatory nature by English fans," said Fifa.
"Proceedings have been opened against The Football Association."
''England hope turns to familiar despair'
'It's the what-ifs that hurt the most'
England were beaten 2-1 in Moscow after extra-time as they attempted to reach a first World Cup final since 1966.
They will end their tournament with a third/fourth place play-off against Belgium in St Petersburg on Saturday.
On Wednesday the FA was fined 70,000 Swiss francs (£50,000) after Dele Alli, Eric Dier and Raheem Sterling wore "unauthorised" socks after ignoring a Fifa warning to stop.
The players wore branded ankle support socks over official Nike socks, "breaching media and marketing regulations and the Fifa equipment regulations".
Doping tests negative
Fifa announced on Thursday that so far all doping tests conducted before and during the World Cup have yielded negative results.
Since January 2018, a total of 2,037 tests have been conducted, Fifa said. On average, every player from the four remaining teams has been tested four times since January, with some of tested up to eight times.