The Bihar government led by Nitish Kumar will initiate action against Railway Minister Lalu Prasad Yadav and his wife and former chief minister Rabri Devi  for using their former official residence of 1 Anne Marg for commercial purposes and spending nearly Rs 4 crore on alterations and additions on the property.

Sources in government said a case will be filed against Lalu and Rabri for misusing the official residence of chief minister and for spending huge amount of tax payers' money for additional construction, which were not required.

"A case against them is likely to be filed by early March," sources said.

In January, a non governmental organisation had filed a public interest litigation in the Patna high court against misuse of the official residence by Lalu and Rabri for commercial purposes.

Lalu and Rabri had vacated the former official residence on February 2 and shifted to their new official residence at 10 Circular Road after much pull and pressure by the new government for over two months.

Now the bungalow is ready for Chief Minister Nitish Kumar, who will probably shift by next week.

The state building and construction department has been demolishing all illegal constructions including a stable, cow menagerie, an out-house, a pond, and a fancy conference room constructed during the 15-year-long stay of Lalu and Rabri in the sprawling bungalow.

"In a bid to gather evidences of waste of government funds, the existence of illegal construction has been videographed," an official said.

According to an official preliminary scrutiny of the expenses incurred by Lalu and Rabri in developing the place to their liking and to accommodate their animal farm, the figure is nearly Rs 4 crore -- all at the cost of taxpayers' money.

The building construction department official said not only the Yadavs made illegal construction on a government property, they used it for commercial purposes while keeping the profit in their pockets. It's all mentioned in his annual tax returns.

Any profit made out of a government property should have gone to the government exchequer, but they instead kept the money for themselves, officials said.