Viktor Troicki has been banned for 18 months for a violation of the Tennis Anti-Doping Programme, the International Tennis Federation has announced.

The 27-year-old Serb failed to provide a blood sample when requested during in-competition testing at the Monte Carlo Masters on April 15.

Troicki claimed he had asked permission to be excused the blood test due to feeling unwell, but that explanation was rejected by the governing body.

His suspension begins immediately and will end on January 24, 2015. Troicki must also forfeit all prize money and rankings points earned at the Monte Carlo Masters.

Troicki, whose highest world ranking was 22nd at the end of 2011, captured his first ATP title in Moscow in 2010, defeating Marcos Baghdatis in his third final. He also helped Serbia win their first Davis Cup title by clinching the fifth and decisive rubber over Michael Llodra.