Abuse of Terengganu's Francis Forkey Doe, 26, began in the warm-up of Tuesday's Malaysia Cup quarter-final second leg against Singapore's Lions XII, and was also directed at a dark-skinned linesman, according to witnesses.
"There was a group of maybe seven or eight fans at the opposite end of the grandstand who were making racial slurs... Orang hitam (black man) and even nigger also came out," undergraduate Muhammad Nadjad Bin Abdul Rahim, 24, told AFP.
"The rest of the crowd would cheer these guys and some joined in," he added.
Racist jeers were also heard when the linesman awarded a throw-in for Terengganu in an incident involving Doe.
"A guy made a comment 'sama (same) colour' and there was a big cheer," Muhammad said.
Doe, who had incurred the wrath of Singapore fans over an incident in which Hariss Harun was sent off in the first leg, made the rude gesture to fans during the warm-up, the witness added.
"They kept calling me 'monkey' and 'black' and I didn't appreciate that... Why call me those names? Because I'm black? Because I'm African?" the player told Singapore's The New Paper.
"Football is a game, a friendly game. You can't say things like that. It's not right."
The Football Association of Singapore (FAS) said it had not been informed of the incident, but stated that it took a strong stance against racism.
"We have a zero-tolerance policy for any form of racism and have always stressed that there is no place for racial discrimination in our society," a spokesperson from FAS said.
Race cases have hit the headlines in football recently with former England captain John Terry facing charges of alleged racial abuse. In Italy, Lazio and Juventus were both fined with week for racist chanting by their fans.
Terangganu reached the Malaysia Cup semi-finals 1-0 on aggregate.