Former British number one Elena Baltacha has announced her retirement from tennis with immediate effect. br The 30-year-old, who won 11 singles titles, reached the third round of Wimbledon in 2002 and the same stage of the Australian Open, in 2005 and 2010. br The Scot reached a career-high ranking of 49 in 2010, but struggled with injury and illness during her career.