Tennis legend John McEnroe has vowed to support his troubled son after he was arrested and charged with drug offences.

Kevin MCEnroe, 27, whose mother is actress Tatum O'Neal, was detained by police in New York City on Tuesday night (15Jul14) after he was allegedly caught making a drug transaction.

He was charged with criminal possession of a controlled substance before being released without bail, and now his famous father has pledged his support.

A statement from MCEnroe reads, "The entire MCEnroe family is extremely upset with regard to recent developments about Kevin MCEnroe. This is a private matter and his entire family will do everything we can to support Kevin as he works through his issues at this very difficult time."

O'Neal has also publicly backed her son. The actress, who has suffered addiction issues in the past, posted a number of family snaps on her page after the arrest, and added a picture of herself with Kevin alongside the message, "Addiction is a disease. Not a moral issue. Support, empathy, love."