NEW DELHI (REUTERS) - India's main opposition Congress party says it is struggling to find enough helicopters to ferry its leaders ahead of a general election, accusing Prime Minister Narendra Modi's ruling party of hogging resources.

Chartered aircraft are a critical part of elections in India, a massive country of 1.3 billion people where national leaders like Mr Modi and Congress president Rahul Gandhi often address multiple rallies in a single day.

But an official with Congress, which is hoping to make a comeback after a massive electoral thrashing at the hands of Mr Modi's Bharatiya Janata Party (BJP) in 2014, told Reuters on Wednesday (Jan 23) the ruling party had already reserved much of the entire available fleet of helicopters in the country for 90 days instead of the usual 45 days.

The official declined to be identified, but senior party leader and former minister Anand Sharma said the BJP had "preempted everything" ahead of the elections due by May.

"Most of them have been cornered by the BJP because they have massive resources and money at their disposal. They've pre-booked most of the fleets," Mr Sharma said. "On a scale of 100 (in terms of resources), they are 90, we are 10."

The BJP denied the charge, calling Congress a "machine of lies".

The alleged shortage of aircraft for Congress reflects the widening gap in resources available with both parties as they head into what will be the world's biggest elections.

In 2017/18, the BJP's total income including donations stood at 10.27 billion rupees (S$196 million) compared with 1.9 billion rupees for Congress, according to the Association for Democratic Reforms (ADR), a Delhi-based advocacy group that examines political funding and candidate disclosure forms.

More than half the income for both parties came from unknown sources, an ADR analysis showed.