China and India are facing a cancer crisis, with smoking, belated diagnosis and unequal access to treatment all causing large-scale problems, experts said on Friday.

In a major report, published in The Lancet Oncology, more than 40 specialists warn that Asia's big two emerging giants are facing huge economic and human costs from the disease.

India's election authorities Friday ordered police to investigate remarks by a top aide of prime ministerial frontrunner Narendra Modi that were allegedly aimed at inciting communal violence.

The powerful Election Commission also barred Modi's aide Amit Shah, 50, from holding public rallies, meetings and roadshows to keep a check on what it called his "undesirable activities."

Maoist rebels killed three soldiers guarding polling officials in central India on Wednesday, highlighting security concerns in the world's biggest elections as the second phase of voting got under way.

The rebels staged the attack in Chhattisgarh state in the country's insurgency-racked center one day before polling is held there, as voters in the restive northeast of the country cast their ballots.

Three Israeli diplomats accused of abusing and injuring an Indian immigration official at New Delhi airport are being "repatriated to Israel", an embassy official told Agence France Presse on Tuesday.

Delhi Police had lodged a criminal case against the consular officials, who enjoy diplomatic immunity, after a scuffle broke out between them and an immigration official late Saturday.

Suspected rebels in Indian Kashmir have shot dead a soldier and two policemen, officials said Tuesday, two days before voting begins in the region for the national election.

A gunbattle late Monday in Kralpora village, 130 kilometers (81 miles) northwest of the main city of Srinagar, left one soldier and two policemen dead.

An overcrowded bus plunged off a mountain road into a gorge Monday in northern India, killing 17 people, police said.

"The death toll has gone up to 17. All the bodies have been removed from the gorge," senior police official Sumedha Dwivedi told AFP.

An explosion killed two policemen Monday in north India, police said, on the same day that national elections kicked off in the world's largest democracy with security high across the country.

The policemen were killed in the explosion of a bomb they were trying to defuse in Aurangabad district, 150 kilometers (93 miles) from Bihar state's capital Patna.

Indians began voting Monday in the world's biggest election, which is set to sweep the Hindu nationalist opposition to power at a time of low growth, anger over corruption and warnings about religious unrest.

The 814-million-strong electorate is forecast to inflict a punishing defeat on the Congress party after its decade-long rule and elect the Bharatiya Janata Party (BJP) led by conservative hardliner Narendra Modi.

Hindu hardliner Narendra Modi, front-runner for premier on the eve of the world's biggest election, accused India's ruling Congress party of failing Muslims as his own party battled claims of fueling religious tensions.

Modi, who is tipped to win power on a promise of reviving the country's battered economy and creating jobs, also urged voters to give him a strong mandate during the marathon six-week ballot which starts on Monday.

A New York police officer's arrest in India has sparked accusations of revenge over the detention last year of an Indian diplomat in New York, but India said Saturday there is no connection.

The police officer, identified as Manny Encarnacion, was detained at the airport in New Delhi after bullets were found in his luggage, a violation of Indian laws against firearms.