Besides seeking the PM's resignation, the BJP demanded that the allocation of 142 coal blocks be cancelled.
The government promptly rejected both the demands, maintaining that it had initiated action to cancel the allocations of those who did not commence production in the allocated blocks.
Finance minister P Chidambaram took serious exception to the use of the phrase, "mota maal".
"If you can accuse the UPA government of receiving 'mota maal', what about the allocations made between May 1998 and May 2004 (during the NDA rule). They should avoid (making) sweeping allegations."
Singh, who leaves for a three-day visit to Iran on Tuesday, appealed to the Opposition to agree on a debate.
"Once again I appeal to the opposition to come back to the House to debate all these issues and let the country judge where the truth lies," he said.
But the BJP rejected his appeal and claimed the support of its NDA allies - SAD, JD(U) and Shiv Sena - and parties such as the AIADMK in its demand for the PM's resignation on moral grounds.
"We don't stand alone. And on corruption, even if we have to fight alone, it would be majestic isolation. The support of the people is with us," said Arun Jaitley, leader of the opposition in Rajya Sabha.