Extra non-competancy clause added in relieving letter which was not there in offer letter during joining

I joined a company which had niether any bond nor any non-competency clause during joining. I worked there over for 3 months as a Software Trainee .After resignation i got a relieving letter from previous company that has an extra clause of non-competancy .It states that i can not join any company which is either a direct competant or indirect competant of the previous company for 3 years. Although i have never signed any such agreements. Please help.

Such a clause is illegal or not valid. But the employer where you are joining should be convinced that the same is violative of section 27 of the Contract Act and thus void. Therefore, if the new employer is not bothered about the clause which prevents you from joining a competitor, forget about the letter.