Astanas Matthias Kessler has tested positive for testosterone following a surprise control in Charleroi in April.

The 28-year-old German, who joined the Astana team from T-Mobile this year, has five days to request the B sample be tested, which he confirmed he will do.

"This result is for me inexplicable and I will immediately require a second assessment," he said.

Kessler has been suspended by the Kazakh outfit pending the result of the second test.