KOLKATA: Vote counting in key Indian state elections was underway Monday under tight security, with the focus on West Bengal, where Prime Minister Narendra Modi's party is hoping for crucial gains.

Elections in five states and territories took place in April and May, and Modi's Bharatiya Janata Party (BJP), the ruling party in the national parliament, is hoping to make inroads into opposition-held states.

In West Bengal, the Hindu-nationalist BJP waged an aggressive bid to dislodge Chief Minister Mamata Banerjee, the firebrand leader of the All India Trinamool Congress (TMC), in power in the state of 100 million people since 2011.

Exit polls last week predicted the BJP has a slight edge over TMC, although exit polls have a patchy record in India.

"The entire country has its eyes on this state's election results," political analyst Biswanath Chakraborty told AFP, in the main city Kolkata. "The contest can tilt the balance of power."

The campaign this time was marked by protests over the removal of millions of names from voter rolls, billed as removing ineligible voters, but which critics said was skewed against marginalised and minority communities.

Banerjee, speaking ahead of the count, insisted her TMC would win.

"The BJP is not coming, take my word for it," she said. "Be patient till the last."

But West Bengal's BJP chief Samik Bhattacharya told AFP he was confident of a win.

"It was an election of rejection," he said. "People of the state want change. The ruling Trinamool Congress will be defeated."

Past elections have resulted in violence in the state.

In the southern state of Tamil Nadu, a key industrial hub with more than 80 million people, the ruling Dravida Munnetra Kazhagam (DMK) under Chief Minister MK Stalin is widely expected to be re-elected.

Votes are also being counted in Assam, an eastern state of more than 31 million which the BJP is widely expected to maintain control of, and the small coastal territory of Puducherry, where the BJP is part of a ruling coalition.

In Kerala, the tightly contested race in the southern state of approximately 36 million, exit polls suggest the Congress party-led alliance is tipped to oust the Communist party.

Wins in the state elections would put Modi on a stronger footing while battling a series of economic and foreign policy challenges, including high unemployment rate and a pending US trade deal.

Indian state elections

India's Modi faces key test as vote count underway