Hi Radhika,
As i read through your mail, I feel there can be multiple reasons and solutions to it. I am putting some as below, please let me know your views.
1. Please speak with the employee and understand the actual reasons, if he has some justifiable concern then management should support him.
2. If he is doing it deliberately, out of arrogance of being a good performer, then based on his capabilities you can redefine his target. Enhance his targets so that he don't get any time to avail leaves.
If his performance deteoriate then, you have all the reasons to question him.
Please share your views on this solution.
Regards
Smarika