NEW DELHI, June 15 (Reuters) - A veteran public health expert warned top Indian officials in early March that a new variant of the coronavirus was spreading quickly in a rural district in the heart of the country and that the outbreak required urgent attention.

Federal health authorities failed to respond adequately to that warning, Dr Subhash Salunke, who has 30 years of experience in public health in India, Indonesia and the United States, told Reuters.

The variant's first impact was detected months earlier in the Amravati district of the western state of Maharashtra, where health authorities recorded a rapid increase in coronavirus infections in early February, even as cases fell elsewhere in India.

Salunke, a former WHO official advising the Maharashtra government, said he alerted some of India's most senior health officials in early March, speaking on the telephone to Prime Minister Narendra Modi's main coronavirus adviser, V.K.

Salunke told Reuters he warned both Paul and Singh that the virus was showing signs of mutating in Amravati, that its transmissibility was increasing, and requested federal help in sequencing more samples to establish how the variant was behaving.

"In spite of a public health person like me giving them a sound warning, they did not take heed," Salunke told Reuters.

He rejected Salunke’s accusation that he did not take heed, saying he requested that India’s National Institute of Virology (NIV) study the variant more closely, and told the Maharashtra state government to intensify its existing response to the virus.

In India, the dramatic rise in infection numbers from April onwards - partly driven by the variant, according to public health studies - overwhelmed the country's health system, causing hospitals to run out of beds and oxygen and causing crematoriums and graveyards to overflow.

That sense of optimism was sweeping large parts of India, including Amravati, where cases had dropped to a trickle, according to local health officials.

Within a few days, he told Reuters, state health authorities sent samples from Amravati to the NCDC for further genetic sequencing to establish if a variant was present.

In late February, federal and local officials had a meeting to discuss the spike in Amravati, according to a senior government scientist who attended it.

At the meeting, Maharashtra's State Surveillance Officer Dr Pradip Awate said the rise in cases was due to voters flocking to local elections held in January rather than any kind of new variant, the scientist who attended the meeting told Reuters.

Missing the rise of the variant in Amravati in late February was a "major mistake", said the scientist who attended the Maharashtra meeting

Between March and April, the federal government allowed the Kumbh Mela Hindu festival to proceed in northern India, drawing millions of people from around the country for a holy dip in the Ganges, many of whom travelled back home carrying the virus, according to public health officials