"The Nitish Kumar government is killing democracy. It is breaking parties in Bihar," Lalu Prasad told reporters here.
"He (Nitish Kumar) gave bribes of crores of rupees," he said, adding that he would be meeting the governor over this.
On Tuesday, 16 of the 22 RJD legislators attended a legislature party meeting at the official residence of former chief minister Rabri Devi.
RJD leaders said four rebel legislators - party chief whip Samrat Choudhary, Raghavendra Pratap Singh, Javeb Iqbal Ansari and Akhtarul Iman - did not attend the legislature party meeting and two did not turn up as they were in their constituencies.
After the meeting, Lalu Prasad alongwith party legislators took to the streets to protest the alleged role of assembly Speaker Uday Narain Choudhary in the bid to split the RJD. He said he will also stage a sit-in at Raj Bhavan.
Lalu Prasad, who arrived here from Delhi, accused Nitish Kumar of offering lucrative posts to his party legislators to defect.
"Nitish Kumar is eyeing RJD legislators and offering them lucrative posts to split the party," Lalu Prasad told media persons.
However, the RJD chief claimed that nine of his 13 legislators returned to the party and denied any split.
In events that unfolded Monday, the RJD looked headed for a split after 13 legislators said they were no longer with the party, and that they intended to join the JD-U.
But later, party leader Abdul Bari Siddiqui denied any rift, while six of the "rebels" said they were still with Lalu Prasad's party. Late Monday night, three more RJD legislators said they were with the party.
The RJD has 22 members in the 243-member house, while the JD-U has 118 legislators.
On Tuesday, RJD leader Raghuvansh Prasad said the speaker was also to be blamed.
"The speaker should have imposed the anti-defection law," he said.
The RJD will issue show cause notice to four rebel legislators who did not attend a meeting of its legislature party. They will be asked to explain their stand over their move to split the party, Siddiqui said.
He said the party will take action against the four only after their clarification.
"The party would request the state assembly to end their membership after their explanation over their act," he told media persons in the assembly premises.
Siddiqui said nine of the 13 legislators submitted letters to the assembly secretary, saying that they were still with the RJD.