London - England's Dele Alli said he was having "a joke" with team-mate Kyle Walker after he was caught on camera raising his middle finger during Monday's 2-1 win over Slovakia.
"Just to clarify, the gesture tonight was a joke between me and my good friend Kyle Walker!" Alli wrote on Twitter after the game.
"Apologies for any offence caused! Great win 2nite."
Television footage of the World Cup qualifier at Wembley showed Tottenham Hotspur midfielder Alli make the gesture in the 77th minute of the game, but it was not clear at whom it was aimed.
Pictures and video footage of Alli's gesture were widely shared on social media, but manager Gareth Southgate played down the incident.
"Kyle and Dele were mucking about and Dele's made a gesture towards Kyle," Southgate told reporters at Wembley.
"The pair of them have a strange way of communicating! But that's what they've said when it's been raised."
Alli, 21, has had a number of run-ins with the football authorities and has faced calls to curb his fiery temperament.
He missed the Premier League title run-in in 2015-16 after punching West Bromwich Albion's Claudio Yacob and was sent off for a dangerous foul on Gent's Brecht Dejaegere during a Europa League game last February.
Marcus Rashford was England's saviour against Slovakia, atoning for an error that gifted Stanislav Lobotka an early opener by setting up Eric Dier's equaliser and then netting a fine 59th-minute winner.
England now require just two points from their last two games, at home to Slovenia and away to Lithuania, to qualify for next year's World Cup in Russia.