NEW DELHI - India's main opposition Congress party Sunday won a crucial parliamentary by-election in northern state of Punjab, decimating the ruling Bharatiya Janata Party (BJP).

Punjab Congress chief Sunil Jakhar, who contested for the parliamentary seat, swept the by-election by trouncing BJP candidate Swaran Salaria by nearly 200,000 votes. Delhi's ruling, anti-graft Aam Aadmi Party, which had also put up a candidate, was also heavily defeated.

The Gurdaspur parliamentary seat in Punjab has fallen vacant after the death of Bollywood actor-turned-politician Vinod Khanna in April. Khanna, a BJP parliamentarian, had won the seat for four consecutive terms.

Punjab is ruled by Congress party which came to power six months back, defeating a BJP-led coalition that ruled the state for 10 years.

State Chief Minister Amarinder Singh was among the first to congratulate Jakhar.

"Congratulations to @sunilkjakhar ji for his impressive win in #Gurdaspur bypoll... Assure people of #Gurdaspur that every single promise made by @sunilkjakhar will be fulfilled and all development works will be fast-tracked," he tweeted.

Jakhar said his win was a "referendum" on the BJP-led National Democratic Alliance's rule in India. "The people of Gurdaspur has sent a strong message of their resentment to the policies pursued by the Indian government," he told the media.

The BJP has not yet commented on its huge loss in the seat that was the party's stronghold in Punjab for years.

The general election in India is due in 2019.