India's Hindu nationalist opposition party and its allies are on course to win an overall parliamentary majority in the world's biggest election currently underway, according to a new poll.

The survey by the NDTV network forecast that the opposition alliance led by the Bharatiya Janata Party (BJP) would win 275 seats in the 543-seat Lok Sabha, 16 more than predicted in the last survey a month ago.

The BJP, led by the hardliner Narendra Modi, would win 226 seats but it would avoid the need to find new coalition partners after results are announced on May 16. Its existing allies would push it over the 50 percent threshold, according to the survey released late Monday.

The centre-left Congress party, which leads the current coalition government, would see its tally of seats drop to an all-time low of 92, the same poll projected.

All previous polls have forecast that the BJP-led alliance known as the NDA (National Democratic Alliance) would fall short of an overall majority -- thus forcing the BJP to seek additional partners among a plethora of regional parties after the six-week voting marathon concludes.

If the BJP-led alliance does fall short of a majority, it is widely expected to try and strike a deal with the West Bengal-based Trinamool party which is forecast to win 30 seats.

Another potential partner, a Tamil Nadu-based party led by former actress Jayalalithaa Jayaram, is slated to get 22 seats.

The contest, which is the world's biggest exercise in democracy, began on April 7 and will wrap up on May 12. The results are expected four days later.