A slugfest erupted today between Opposition parties and the government over the coal scam, with BJP holding Prime Minister Manmohan Singh responsible saying he is the final signatory while Union Ministers defending him in unison.

The BJP said Singh is "culpable" if one goes by the rules applied in the Commonwealth Games and 2G spectrum scams, where the final signatory was held responsible for the financial irregularities.

Alleging that trail of the coal scam goes all the way to the Prime Minister since he was the final signatory for all the allocations, BJP also sought to know how Coal Secretary P C Parakh is being held responsible but not the minister who held the portfolio.

"The trail of the coal allocation scam goes all the way to 7, Race Course Road (PM's residence).