Police are investigating an alleged racist gesture made by a person to Tottenham fans during Sunday's Premier League game at Newcastle United.
Spurs won 3-2 in Newcastle's first game following a takeover of the club.
"An investigation is under way and the police have been made aware," said a Magpies statement.
"Discrimination has absolutely no place in football, in the street, online or in wider society and we will not tolerate it under any circumstances."
The club added they "will pursue the strongest possible action against anyone involved in discriminatory behaviour and will support any efforts by the authorities to secure a criminal conviction."
A Northumbria Police spokesperson said: "We can confirm we are investigating an alleged racist incident during Newcastle United's home fixture with Tottenham at St James' Park on Sunday.
"Enquiries are ongoing with the club to identify anyone involved and ascertain whether criminal offences have been committed."
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