"When the government refused a CBI inquiry into the scam, the entire opposition staged a walkout from the state assembly," Leader of Opposition in the Bihar assembly and Rashtriya Janata Dal leader Abdul Bari Siddiqui told IANS. The opposition parties -- the RJD, Lok Janshakti Party (LJP), the Communist Party of India (CPI) and the Congress members -- walked out of the assembly.

Earlier, Siddiqui said in the assembly that the opposition will approach the court if the Janata Dal-United (JD-U)-led state government failed to order a Central Bureau of Investigation (CBI) probe into it.

After taking part in a special debate in the state assembly on the alleged irregularities in the implementation of Mahatma Gandhi National Rural Employment Guarantee Scheme (MNREGS), Siddiqui said Chief Minister Nitish Kumar's government should not delay in ordering a CBI probe into the mega-scam.

Last month, Delhi-based Centre for Environment and Food Security (CEFS) said the performance audit of MGNREGS in Bihar found that 73 percent of the Rs.8,189 crore scheme fund, spent in the state's 38 districts in six years (2006-12), were embezzled by the implementing authorities.

"There is an open loot of taxpayers' money. There is plunder of rural poor's right to guaranteed wage employment for 100 days and there is pillage of every single norm of democratic governance and public accountability," the CEFS report said.

"The scale and dimensions of MNREGS corruption in Bihar suggest that this kind of open loot is impossible without active connivance of the block and district authorities," the CEFS added.

Last week, Bihar Rural Development Minister Nitish Mishra said the government would conduct the physical verification of beneficiaries and areas covered under the Mahatma Gandhi National Rural Employment Guarantee Scheme (MGNREGS).

Mishra assured that strict action would be taken against officials found involved in irregularities in the implementation of the scheme.

MNREGS aims at enhancing the livelihood security of people in rural areas by guaranteeing 100 days of wage-employment in a financial year to a rural household whose adult members volunteer to do unskilled manual work.