Wct deduction on interstate works contract executed in tn

A machinery manfacturer, situated in Maharashntra, has entered into CMC contract with us in Tamil Nadu which includes supply of materials and service.The vendor has charged us CST and Service tax in the invoice.The vendor is not a registered dealier in Tamil nadu.+ The supply and service to be utilised in our company in Tamil nadu. As per TN VAT Act,,we are supposed to deduct WCT TDS on the invoice value. Is this deduction applicable in these type of contracts ? or exempted under TN VAT Act

Please clarifiy

Regards

C.V.Narasimhan