British player Dan Evans has been provisionally suspended after admitting on Friday that he had failed a doping test for cocaine at the Barcelona Open in April.
The world number 50, who reached his first ATP Tour final this year in Sydney and has played for Britain in the Davis Cup, released a statement at a news conference in London.
"This is a very difficult day for me and I wanted to come here in person and tell you guys face to face that a few days ago I was notified that in April I tested positive for cocaine," the 27-year-old from Birmingham said.
"It's really important to know that this was taken out of competition and in a context completely unrelated to tennis.
"I made a mistake and I must face up to it. I do not condone for one second that this was acceptable behaviour," Evans added.
"I've let a lot of people down, my family, my coach, my team, sponsors, British tennis and my fans and I can only apologise from the bottom of my heart."
Evans, who pulled out of this week's grasscourt tournament at Queen's Club due to injury, will be provisionally suspended from June 26 and will not be able to play at next month's Wimbledon championships.
"Mr Evans was charged on 16 June with an Anti-Doping Rule Violation," the International Tennis Federation's Anti-Doping Programme (TADP) said in a statement.
"Mr Evans has accepted the finding of cocaine in his sample collected on 24 April.
"As positive tests for Non-Specified Substances carry a mandatory Provisional Suspension, Mr Evans will be provisionally suspended with effect from 26 June...pending determination of the case."
Evans has enjoyed the best spell of his career in the past 18 months having dropped outside the top 700 two years ago.
After reaching the final in Sydney he made the last 16 at the Australian Open where he lost to Jo-Wilfried Tsonga.
At the Barcelona Open he won his first Tour-level matches on clay, reaching the last 16 before losing to Dominic Thiem.
The Lawn Tennis Association (LTA) said it was "very disappointed" at the news.
"We absolutely condemn any form of drug-taking and will support the process which needs to take place," it said in a statement.
"We are in touch with Dan and we will offer appropriate guidance, support and education to him on how best to address the issues he now faces."
Evans is not the first tennis player to fall foul of cocaine. Frenchman Richard Gasquet escaped with a two-and-a-half month ban in 2009 after an ITF tribunal panel ruled that he inadvertently took cocaine by kissing a woman in a nightclub.
In 2007, former world number one Martina Hingis said she had tested positive for cocaine during Wimbledon that year and promptly announced her retirement from professional tennis.
The Swiss five-times grand slam singles champion was banned for two years but has since returned to the tour as a successful doubles player.