Need to pay one month salary, if not joining

You may go thru the job advertisement, interview call letter and all other communications even if by email.

Is it stated that if the selected candidate does not join he/she will have to pay some cost to company?

Have you accepted the offer made by offer letter to you?

Has the company stated in offer letter that upon joining selected candidate shall have to sign some agreements without naming and specifying the agreements etc………………..or has the company stated so verbally or have you inquired about the details………………….? Has the company paid the expense to attend the interview e.g. by air?

Did you apply thru some job consultant/recruitment agency of the company and has this agency been paid some fee by company?

If you are not comfortable you may refuse to accept the offer and mention the reasons……………..

The company would scream that it has incurred expenses on recruitment etc……………..

However the question arises is it equivalent to one month salary?

You may show all documents to your lawyer. The lawyer that has seen all docs can advice you best. Let your reply to offer letter or any notice by company be also drafted by your lawyer.