Claims that homophobic anti-Chelsea song sheets were distributed at West Ham's London Stadium are being investigated, reports BBC Sport.
Hammers fan Nadeem posted an image of one of the flyers, urging fans to sing homophobic lyrics about Chelsea captain John Terry, on social media.
Nadeem told BBC Radio 5 live that the leaflets were being handed out before the home side's 2-1 EFL Cup win.
"It was quite idiotic and a bit disgusting," he said.
Nadeem told BBC Radio 5 live's Afternoon Edition that the song sheets seemed to be being handed out by "one person being moronic" and said no fans were singing the chant.
The match was marred by crowd disorder with the police making seven arrests.
In a statement, the Metropolitan Police said its investigation into the disturbances will include "a leaflet handed out before the match containing homophobic contents".
West Ham told BBC Sport it was "investigating the alleged distribution of these flyers" and would "take the strongest possible action against those responsible".
Anti-discrimination group Kick It Out said it had "received reports of homophobic literature being distributed" and had reported it to the Football Association, which is also investigating.