Resignation During Probation Period [Thread 331488]

I was working with a Private Limited Company in Thane as a TRAINEE OFFICER - ACCOUNTS from June 1st 2010, with a CTC of Rs. 60,000 p.a. Recently I left the company (in April 2011) because I got better oppurtunity.
I was on Training period of 6 months and Probation period of 6 months, before the completion of my Probation period I left the services, there was no mention of NOTICE PERIOD in the Appointment Letter. Now the employer wants me to complete a notice period of 30 days, although there was no such mention anywhere in the Appointment Letter.
My queries are:
1) Can the Employer take Action against me due to my Immediate resignation?
2) Since I was on Probation period was it mandatory for me to give notice period, although there was no such mention in the appointment letter?
3) What suitable actions can I take against him (Employer), if he tries to harass me by sending mails or over the Phone?
4) What are the Legal steps I can take against him to challenge him?

Dear Kaushal,
I had been with your offer letter and even there is no such clause mentions that you need to serve notice period...
There is nothing officially that you have to serve notice period over their but i am afraid that your Manager shall might arise probe for giving you the reliving letter / Experience letter.
And as far my knowledge, resource has to serve maximum 15 days notice period in their probation period, if notice clause mention in the Offer letter.
As per your offer letter, the company / manager are not liable to take any action against you but yes you can take action against him
Initial first send a requesting mail to your manager, if he could not listen, then warning mail, even though if they arise any issue then you can approach to Labour Law Court.
Note: Make each and every conversation in documents (EMAIL)