New York - The Association of Tennis Professionals said on Friday it had found no evidence that Ryan Harrison racially abused Donald Young during the duo's ill-tempered New York Open clash this week.

African-American Young, 28, had accused Harrison of making a remark relating to his ethnicity when tempers boiled over in their first round match on Monday. Harrison had emphatically denied the claim.

The two Americans exchanged words in the first set and needed to be separated by the chair umpire during a changeover in play.

The ATP said in a statement it had found no evidence of racism after carrying out an investigation into Young's claim.

"The ATP conducted a full investigation into this week's match at the New York Open between Ryan Harrison and Donald Young," the statement said.

"All available evidence was reviewed including match footage and interviews with match officials and other tournament personnel who were in close proximity of the players.

"Unfortunately, the audio recording on the match footage did not pick up verbal exchanges between the players.

"At this time no evidence has been found to support the allegation that Ryan Harrison used a racial slur during the match."

Young had addressed Harrison on Twitter directly after the match.

"I'm shocked and disappointed, Ryan Harrison, to hear you tell me how you really feel about me as a black tennis player in the middle of our NY match," he said.

Harrison, who won the match 6-3, 7-6 (7/4), was adamant that Young's claim was unfounded, declaring that any audio of their exchange would clear him.

"The accusations made by Donald Young tonight following our match are absolutely untrue," he wrote.

"I'm extremely disappointed that someone would say this in reaction to a lost tennis match. Any video/audio will 100% clear me."