West Bengal Chief Minister Mamata Banerjee on Wednesday congratulated Samajwadi Party leader Akhilesh Yadav, BSP chief Mayawati and RJD leader Lalu Prasad as the opposition took big leads over the BJP in Lok Sabha by-elections.

"Great victory. Congratulations to Mayawatiji and Akhileshji... The beginning of the end has started," the Trinamool Congress leader tweeted.

"Congratulations to Lalu Prasadji for winning Araria and Jehanabad. This is a great victory," she said. Officials in Patna said the vote count was still on.

The Samajwadi Party, backed by the BSP, took winning leads in both the Lok Sabha seats of Phulpur and Gorakhpur in Uttar Pradesh. The RJD was leading over the BJP in the Lok Sabha seat of Araria in Bihar.