Indian Prime Minister Narendra Modi visited Assam on Friday, announcing multi-billion-dollar investments as part of a tour of states heading into elections, including the key political battleground of West Bengal.

The Hindu nationalist leader launched infrastructure projects in Assam — including land holdings to tea plantation workers, a dam project and a major train and road corridor — worth over $5 billion.

The northeastern state of about 32 million people is controlled by his right-wing Bharatiya Janata Party (BJP).

On Saturday, Modi will visit neighbouring West Bengal, a state of 105 million people led by his political rival Mamata Banerjee, of the All India Trinamool Congress party.

During the visit, he is expected to inaugurate “road infrastructure, railways, port and shipping” projects worth roughly $2 billion, which his office says are aimed at “accelerating economic growth”.

State elections this year will be held in the southern states of Kerala and Tamil Nadu, both under opposition parties, as well as the smaller coastal territory of Puducherry.

Of these regions, only Assam is currently under full BJP control.

The Election Commission is expected to announce polling dates later this month, with voting widely anticipated to take place in April and May.

Modi visited Tamil Nadu earlier in March, a southeastern state with some 72 million people, where he unveiled investments of more than $600 million, including in a petroleum-related manufacturing project, roads and railways.

He also visited Kerala, with around 33 million people, where he unveiled a $1 billion worth of projects, as well as Puducherry.

The contest in Kerala is between the main national opposition, Congress party, and the ruling alliance of left-wing parties, led by the Communist Party of India (Marxist).

Past elections in West Bengal and Kerala have seen violent political clashes in the run-up to polls.