Prominent Indian artists and academics have written an open letter warning against the possible election of Hindu nationalist politician Narendra Modi.
The letter - signed by writer Salman Rushdie and sculptor Anish Kapoor among others - attacked Modi's record in the 2002 Gujarat riots.
Modi, a candidate for the opposition BJP in the current election, is seen as a likely next prime minister.
A BJP spokeswoman dismissed the letter as baseless and "hate-mongering".
"The courts in India have examined all evidence and have found nothing to link Modi to the riots," spokeswoman Nirmala Sitharaman told the BBC.
"If people like Kapoor still talk like this, it raises questions on whether they trust Indian courts," she said.
Modi was cleared by an investigation of any involvement in the 2002 riots, one of India's worst outbreaks of religious violence.
He was chief minister of Gujarat state when more than 1,000 people, mostly Muslims, were killed in attacks that followed the deaths of 60 Hindus in a train fire.
His critics accuse him of having tacitly permitted the violence.
Modi has always denied any responsibility - but nor has he expressed any remorse or offered any apologies for the riots.
The BJP leader's supporters say he is a dynamic and efficient leader who has made his state an economic powerhouse.
The open letter - published in the UK's Guardian newspaper - said Modi's "failure of moral character and political ethics" in Gujarat was "incompatible with India's secular constitution".
"Were he to be elected prime minister, it would bode ill for India's future as a country that cherishes the ideals of inclusion and protection for all its peoples and communities," the letter said.
The letter was signed by more than a dozen internationally renowned Indian artists and academics, many of them based in the US and the UK.
The signatories also included several British MPs.
Salman Rushdie, Anish Kapoor lead anti-Modi charge in UK media - NDTV http://t.co/ivcgBTes9R
— Narendra Modi News (@NModiNews) April 12, 2014
Kapoor compared Modi's claims that he was a Hindu nationalist because he had been born a Hindu to statements by India's independence hero, Mahatma Gandhi, who professed to belong to all faiths.
"Gandhi spoke for all of India," he told the BBC. "Modi does not."
Salman Rushdie, Anish Kapoor lead anti-Modi charge in UK media http://t.co/Vg3xmBUbeI
— NDTV (@ndtv) April 11, 2014