A court in Patna, capital of Bihar state, ordered Yadav to be sent to a maximum security jail, while his wife, Rabri Devi, was allowed bail because of her status as Bihar's chief minister.

Rabri Devi: Released on bail

Charges relating to bribery and corruption were filed against the couple on Tuesday by India's Central Bureau of Investigation (CBI).

The judge at the special CBI court in Patna described the charges against them as "very serious".

The charges follow a two-year investigation into allegations that millions of rupees set aside for farm subsidies had been misappropriated.

Rabri Devi was sworn in as chief minister for a second time three weeks ago after a lengthy political stalemate caused by inconclusive state elections.

Her husband's Rashtriya Janata Dal (RJD) party beat the National Democratic Alliance, the ruling coalition in Delhi, by just a couple of seats.

The BBC's Satish Jacob in Delhi says the latest developments could mean the recent political uncertainty in the state will continue.

Calls to quit

Following the charges, the NDA has called for Rabri Devi to step down as chief minister.

"This is the first time a chief minister has surrendered before a court. So she must quit on moral grounds," NDA leader Nitish Kumar told journalists.

However, the RJD says the charges are baseless.

Yadav, a charismatic low caste figure who has become Bihar's chief power broker, was sent to jail two years ago for his alleged involvement in a colossal scandal involving millions of rupees, and was forced to resign as chief minister.

He shocked the country by his decision to make his wife, Rabri Devi, his successor.

She is illiterate and had no experience of politics.

She became a mere figurehead, and Laloo Prasad Yadav continued to run the state by proxy from his prison cell.

Bihar is one of India's poorest states and is racked by crime and caste violence.