Macclesfield captain Nat Brown was allegedly a victim of racial abuse during a 1-1 draw in their FA Cup clash at Barrow on Tuesday evening, according to manager Steve King.
Brown was seen having an exchange with supporters as he made his way out of the tunnel at Holker Street prior to the start of the second half. The 31-year-old later claimed there was a racially-based verbal attack on him, and King confirmed a complaint had subsequently been lodged with match officials.
"He got called a monkey by some of the fans behind the goal," said King. "He said to the ref, he's called me a monkey and that's not acceptable.
"I heard it when I was coming out with Nat Brown. It seems to be happening everywhere," King said.
As for whether Brown wanted to take the matter further, King said: "It's up to Browny - he said leave it but the ref [David Webb] wants to report it because it's not acceptable. We're in 2012 - what's all that about?"
Barrow assistant coach Ashley Hoskin says he was aware of the allegation and said his club would take firm action if they could pinpoint any offenders.
"It was actually their manager who came over and said someone had shouted something at one of their players," Hoskin said.
"If that's the case, it's not acceptable. It's not acceptable in any walk of life, never mind football, and it's very disappointing if that's happened.
"I know for sure the club would take a stance on anyone shouting what was allegedly shouted."
The Football Association has confirmed it is investigating the claims. Referee Webb included his version of events in his report of the match, which will go to a December 29 replay to determine who will face Championship side Cardiff in the third round.
A spokesman for the FA said: "We are aware of the incident and it was referenced in the referee's report. We are now liaising with both clubs and the police.''
Information from the Press Association was used in this report.