Service tax input

Dear Friends,

I have come across this problem while working for one of the clents of our Firm. Please answer asap if possible :

The client company is a an engineering construction company having sites all over India. The client has deducted service taxes against bills of it's subcontractors throughout the F.Y. 2011 - 2012 but has not claimed input credit for the same in it's payments to subcontractors for Service Tax over the year.

Question is : Can the client claim the previous input credits (since April,  2011) against amounts it will pay now  i.e., in March 2012 ? The total unclaimed input credit amount is around Rs. 3 Lakhs.  

Thanks and regards.