Voting has begun in elections in two Indian states, where PM Narendra Modi's BJP is facing a tough fight against a powerful regional party and the main opposition Congress.

More than 13 million voters are eligible to cast ballots in West Bengal and Assam states on Monday.

The elections are the first phase of staggered polls in both states.

Assembly elections are being held in five Indian states in April and May. Votes will be counted on 19 May.

In the eastern state of West Bengal, where polling is being held in 18 of its 294 seats, the BJP is seen as having little chance against the regional Trinamool Congress party, led by the state's chief minister Mamata Banerjee.

However, in Assam where votes are being cast in 65 of the 126 seats, Mr Modi's party stands a chance of winning, correspondents say.

Ethnically diverse and prone to conflicts, Assam has been ruled by the Congress since 2001.

The BJP has tied up with local parties that support rights of local tribes-people and are opposed to illegal migration, to take on the ruling party.

Voting will be held in Tamil Nadu, Kerala, Assam, Bengal and Pondicherry between 4 April to 16 May.

In eastern West Bengal and southern Tamil Nadu states, regional parties are expected to dominate. In the southern state of Kerala, it will be a fight between left parties and the Congress.

"The BJP is clearly not doing well in the state elections, and if they do not win one in 2016, they would have gone without having won a single state election for nearly two years, which is not good for any party," Neelanjan Sircar, a senior fellow at the Delhi-based Centre for Policy Research told the AFP news agency.

Voting will be held next in West Bengal on 17, 21, 25 and 30 April, as well as 5 May.

Assam will go to polls next on 11 April.

The southern states of Tamil Nadu, Kerala and Pondicherry will all vote in a single phase on 16 May.

(BBC)