Service tax input to excise for manufacturing company

Dear Experts,

We are the Manufacturing company and we only registered with the Excise Department. Now some Sub Contractors are charging Service Tax and we have the doubt that whether we can take the Service Tax as input while paying the Excise Duty.

Hence I request you to explain me that, Whether we can take the Service Tax Input and Adjust with the Excise Duty. And is it must to get registered with the Service Tax Department.

Please Explain.

Thanks in Advance.

ANTONY RAJ

Bnagalore