Set off of service tax payable with excise duty

Dear Sir,

The builder who is engaged in construction of residential complex and opted for payment of service tax @ 10.3% on 33% of Construction Cost is eligible to set off his service tax liability with Excise duty [Excise duty taken from Steel Purchase Invoices & Cement Purchase Invoices].

Is the above statement true?

If it is true, then will it be applicable to Works Contractors who opted for Composite Scheme for Payment of Service Tax @ 4.12%?

Under what circumstances Excise duty paid on material purchases can be availed to setoff from Service Tax Payable?

Kindly reply even if partial answer is known...

Thanks in Advance!!!