Roger Federer's [ Images ] wife Mirka has given birth to twin girls, the world number one announced on his website on Friday.

The 15-times grand slam winner said Charlene Riva and Myla Rose had been born on Thursday in Switzerland [ Images ].

"This is the greatest day of our lives," Federer said on the website (www.rogerfederer.com).

"Mirka, Myla and Charlene are all healthy and doing very well."

The couple were married in a small ceremony in Basel (Switzerland) in April this year.

Earlier this month Federer won his 15th grand slam title defeating Andy Roddick [ Images ] in the four hours and 16 minute Wimbledon [ Images ] final.

The win helped him break American Pete Sampras's [ Images ] record of 14 grand slam titles as well as reclaim the world number one spot from rival Rafael Nadal [ Images ].

His win at the French Open [ Images ] in June also made him only the sixth man -- after Fred Perry, Don Budge, Rod Laver, Roy Emerson and Andre Agassi [ Images ] -- to have won all four grand slam titles during their careers.