Dear Shyamprasad Rao,
Though you have raised a query, you have not mentioned in what capacity do you work in the Govt Corporation? Are you an officer or a lower cadre employee?
Employees in general, whether from government services or semi-government services or the private organisation do some amount of personal work during office hours. Therefore, as a corollary, if they do some amount of work during their leave then nothing wrong per se.
Nevertheless, the government employees sign certificates or other important documents in the course of their work. These approvals or their official decisions should not create a problem for them. Should some enquiry were to take place, the question could be raised as to why the government employee had given some approvals in spite of being on leave.
In government services, anything and everything happens with the approval from a "competent authority". Therefore, I recommend you taking approval for the work that you will be required to do while on leave. This approval will give protection in case if of any unforeseen circumstances.
Thanks,
Dinesh Divekar