The CBI on Tuesday started questioning former railway minister Lalu Prasad in connection with the land for jobs scam case where people were allegedly given jobs in the railways in return for land parcels gifted or sold at cheap rates to the Yadav family and associates, officials said according to PTI.

The examination of the RJD supremo comes a day after his wife and former Bihar chief minister Rabri Devi was quizzed at her Patna residence by the agency for nearly five hours, they said. According to officials, a team of five CBI officials arrived in two cars at 10.40 am at the residence of Misha Bharti in Pandara Park on Tuesday where Prasad is currently residing and the questioning will continue during the day.

The Central Bureau of Investigation (CBI) has already filed a charge sheet in the case against Prasad, Rabri Devi and 14 others under charges of criminal conspiracy and provisions of the Prevention of Corruption Act, in which all the accused have been summoned on March 15, they said.

The charge sheet alleges that railway job candidates hailing from Patna were chosen as substitutes for Group D posts in the railway division of Mumbai, Jabalpur, Kolkata, Jaipur, and Hajipur. In return, plots of land were said to be transferred to Yadav's name or sold at throwaway rates as reported by ndtv.com.

The CBI said a fresh round of questioning is taking place as part of "further investigation" where the investigation agency is trying to ascertain the money trail and larger conspiracy. The fresh questioning of ailing Prasad, who was convicted in a fodder scam, and his wife had evoked sharp criticism from opposition parties on Monday.

Prasad's son and Bihar Deputy Chief Minister Tejashwi Yadav termed the CBI action a result of his family's "relentless opposition" to the Bharatiya Janata Party (BJP).

"It is an open secret that probe agencies are acting against political opponents of the BJP and helping those who agree to align with that party," the RJD leader told reporters outside the Bihar Assembly on Monday.

Yadav said as the then railway minister, Prasad, had "no powers" to give employment in exchange for favours.

He got support from the Congress and the AAP which targeted the central government alleging that the saffron party wanted to "suppress" the voice of the opposition.

"Today Rabri Devi ji is being harassed. Lalu Prasad ji and his family have been harassed for years because they did not bow down," Congress general secretary Priyanka Gandhi Vadra tweeted.

AAP convenor and Delhi Chief Minister Arvind Kejriwal said targeting and harassing opposition leaders is wrong. The CBI had recently arrested the then Delhi deputy chief minister Manish Sisodia in the excise policy scam case.