India's right-wing ruling party secured strong victories in two important state elections, tightening its grip on power after storming to power nationally five months ago.

Prime Minister Narendra Modi's Bharatiya Janata Party (BJP) was assured of victory in Maharashtra, of which financial hub Mumbai is the capital, over its centre-left rival the Congress party which ruled the western state with its allies for 15 years.

Celebrations erupted at BJP headquarters in Mumbai, with supporters lighting firecrackers, feeding each other sweets, throwing flower petals and shouting "Long live Mother India!" - although the party is likely to fall short of an absolute majority.

The BJP won outright for the first time in Haryana, which borders the national capital, New Delhi, handing the once-powerful Congress a humiliating defeat after its 10-year rule of the state, official results showed.

"We are two steps closer to our mission of a Congress-free India," BJP president Amit Shah told reporters in New Delhi.

"Today's results show that the Modi wave is still the tsunami that can destroy," Shah said after supporters placed a garland around his neck.

Despite the wins, the BJP is expected to fall short of a majority in Maharashtra and is seen as needing a partner to form a government.

Economic reforms

The BJP has won or was leading in 122 seats in Maharashtra, in tallies on the election commission's website, while Congress had 42 seats in the 288-member state assembly. Shiv Sena, a former BJP ally, was leading in 63 seats there.

In Haryana, the BJP secured a majority of 46 of the 90 seats up for grabs, and was leading in one more seat, while the Congress party had won or was leading in just 15.

"There was considerable anti-incumbency factor (against us)," senior Congress leader Rajiv Shukla told the CNN-IBN network.

Modi, a popular leader and fiery orator, campaigned for the elections held last week. The victories are likely to encourage him to push ahead with promised economic reforms, some of which could prove unpopular.

The nationalist leader won a landslide victory win at the national polls in May on a pledge to revive the ailing economy and clean up endemic corruption.

On the eve of the results, Modi's government lifted controls on diesel prices in an attempt to give market forces greater influence over the economy, attract investment and cut subsidies.

The defeats are yet another blow for the Congress, whose Gandhi dynasty has produced three prime ministers, following its thumping loss to the BJP in May after 10 years in charge nationally.

Source: AFP