"Along with Congress, (BJP-led) NDA government is also responsible for the Rs 1.86 crore coal scam," Karat told reporters here.
"BJP is not doing the right thing by stalling Parliament on this issue (CAG report on coal block allotment). It should allow Parliament to function," Karat said.
He said "BJP is alone and not even its allies are with it. The parliamentary system should not be disrupted."
He said Left parties had expressed willingness to participate in the debate when the CAG report was placed during the monsoon session itself.
To a question, Karat did not subscribe to BJP's statement that Prime Minister Manmohan Singh should not have read out his statement amid din in Parliament on CAG's report on coal block allotment.
"The Prime Minister had no alternative," Karat said.