New Delhi, Aug 25 (IANS): Former coal secretary P.C. Parakh Monday said all coal ministers post-2004 are responsible for the lack of transparency in allocation of coal blocks.

"All ministers, who held portfolio of coal minister after 2004, are responsible for not implementing a transparent system," Parakh told news channel CNN-IBN.

His comment came after the Supreme Court Monday described all coal block allocations from 1993 onwards as illegal.

The Congress, meanwhile, defended its leaders, saying they followed the model for allocation that was already in place.

"We were following the same pattern adopted by the NDA government. We infact made the process more transparent," said Congress leader Shakeel Ahmad.

"In the NDA, not a single coal block was allotted through advertisement. In UPA, not a single block was allocated without an advertisement," he said.

The apex court held that the coal blocks allocated from 1993 onwards were illegal, arbitrary, non-transparent and were devoid of any procedure.

The court, however, stopped short of pronouncing instant cancellation of the coal blocks as it may have serious repercussions.