Bharatiya Janata Party and its allies are predicted to bag most of the parliamentary seats in the world's biggest-ever election, a majority of the exit polls showed on Monday.

Research group C-Voter forecast 289 seats for the National Democratic Alliance led by the BJP, while another poll, by Cicero for the India Today group, projected the NDA hitting between 261 and 283 seats.

A majority of 272 is needed to form a government, although that is often achieved with outside support from regional parties. Official results will be out on Friday.

Still, several national exit polls over-estimated the BJP's seat share in the last two general elections in 2004 and 2009.

The ruling Congress party went on to form coalition governments on both occasions.