European Union foreign policy chief Catherine Ashton on Tuesday defended Italy's envoy to India, prevented from leaving the country due to a row over two Italian marines who skipped bail while on trial for murder in New Delhi.

A statement from Ashton's office said she "notes with concern" an Indian Supreme Court decision the previous day requiring ambassador Daniele Mancini to seek permission of the court to leave the country.

Police in Indian-administered Kashmir Tuesday said they had arrested four people including a Pakistani national from the Lashkar-e-Toiba militant group over an attack that left five policemen dead.

Abdul Gani Mir, Kashmir's top law enforcement officer, said investigators had concluded that the attack was planned by Lashkar-e-Toiba (LeT), a Pakistan-based group blamed for mass killings in Mumbai in 2008.

A speeding bus careered off a river bridge in western India Tuesday, killing 37 people and injuring another 14, police said.

The pre-dawn accident happened in the Khed area of Ratnagiri district in Maharashtra state, 350 kilometers (220 miles) south of the state capital Mumbai.

Italy on Monday said India was violating a convention on diplomatic immunity by preventing the Italian ambassador from leaving the country in an escalating row over two Italian marines on trial for killing two Indian fishermen.

"The Supreme Court's decision to prevent our ambassador from leaving the country without the court's permission is a clear violation of the Vienna convention on diplomatic relations," the foreign ministry said in a statement.

India's top judge said Monday that the Italian ambassador cannot claim diplomatic immunity in a growing dispute over two Italian marines who skipped bail while on trial for murder.

Chief Justice Altamas Kabir said Daniele Mancini, who had negotiated the marines' release last month so they could vote in Italy's election, had waived his immunity by giving an undertaking to a court that the pair would return.

Five villagers have confessed to gang-raping a Swiss tourist in central India, police said Sunday, in an incident that has renewed focus on the rampant violence against women in the country.

The woman was on a cycling holiday with her husband in impoverished Madhya Pradesh state when six men attacked the couple on Friday night, sexually assaulting the woman and robbing the pair, police said.

A probe into the death of a man suspected of gang-raping a student on a New Delhi bus last December blames jail officials for failing to monitor him adequately, an Indian media report said on Sunday.

Ram Singh, one of six men on trial over the deadly assault which sparked mass protests across India, was found dead in his cell in the high-security Tihar Jail on Monday morning where he had been held since his arrest after the crime.

A Swiss female tourist was gang-raped in rural central India, police said on Saturday, the latest victim of sexual violence against women in the South Asian nation.

The woman was on a cycling trip with her husband in impoverished Madhya Pradesh state, when seven to eight men attacked the couple on Friday night, sexually assaulting the woman and robbing the pair, police said.

India's airports have been put on alert to prevent Italy's ambassador leaving the country amid a dispute over two Italian marines who skipped bail while on trial in Delhi, a home ministry source said Friday.

The source quoted an order faxed to immigration authorities as saying: "Immigration authorities have been alerted that Daniele Mancini should not leave without permission."

India's Supreme Court on Thursday issued an order for Italy's ambassador to stay in the country amid a dispute over two Italian marines who skipped bail while on trial for murder in New Delhi.

A three-judge bench said that ambassador Daniele Mancini, who had negotiated the release of the marines so they could return home to vote, should remain in India until the next hearing about the dispute on Monday.