Last updated on .From the section Golf

Johnson is 16th in the world rankings and has won eight titles on the PGA Tour

Reports suggesting Dustin Johnson has been suspended for failing a drugs test have been denied by the PGA Tour.

On Thursday, the big-hitting American golfer announced he was taking time out to confront "personal challenges".

But Golf.com reported that Johnson, 30, is serving a six-month suspension after testing positive for cocaine.

A PGA Tour statement said: "This is to clarify that Mr Johnson has taken a voluntary leave of absence and is not under a suspension from the PGA Tour."

Announcing his absence, which means he will miss the Ryder Cup in September, Johnson said he hoped the break would improve his "mental health, physical well-being and emotional foundation".

BBC golf correspondent Iain Carter "Reports surfaced in the US alleging he had been banned for six months for a failed drugs test. The PGA Tour doesn't reveal punishments handed out to players, but issued a statement to clarify that Johnson has taken a leave of absence and is not under suspension from the PGA Tour."

Johnson, who also misses the US PGA Championship at Valhalla external-link , was the only unbeaten United States player when Europe triumphed at Medinah two years ago.

As well as missing the final major of the year and the Gleneagles showdown, which runs from 26-28 September, Johnson will also sit out the lucrative PGA Tour play-off series.

The PGA Tour has a policy of not releasing details of positive tests for recreational drugs.

Johnson, who finished 12th at last month's Open at Royal Liverpool and was fifth in the US Ryder Cup list, said he was taking leave of absence from the game with immediate effect.

"I will use this time to seek professional help for personal challenges I have faced," he said.

"By committing the time and resources necessary, I am confident that I will be better equipped to fulfil my potential and become a consistent champion."

Johnson pulled out of the 2012 Masters citing a back injury caused by lifting a jet ski. He missed three months of the season.