The question of "Leave" (leave with pay) does not arise if he is a fresh appointment (irrespective of when he had left the company previously). No law in the statute governing "employment" speaks about not rehiring an associate. This is an internal prerogative of a company whether it can rehire/re-employ a left associate and is generally mentioned in some company policy or could be a prevailing practice.
Now, if the employee had left the company before 1 - 2 months, you should have done his Full & Final Settlement, and the employee should have acknowledged the same. (Hope you would have also considered his "balance leave/s", gratuity - if applicable, bonus - if applicable, other applicable dues while preparing his F&F and would have paid the F&F settlement amount to him).
For you to do his Full & Final settlement, you should have received the resignation from the employee (unless it is a case of termination/retrenchment).
If these events have occurred in a sequence, it's clear that the employment had terminated, and it is a case of re-hire/re-joining.
Again, as per what Suresh has stated, you should have issued a fresh appointment order/letter to the associate, which should have been acknowledged by him.
In such a scenario, the employee's claim of having taken 5 leave (I believe he means 5 weeks) is irrational.
Cheers,
A.B.