India opposition rally blasts toll now six

The death toll from a series of crude bombs targeting supporters of Indian opposition leader Narendra Modi has risen to six, a doctor says.

Seven small bombs planted by six suspects and linked to timers exploded on Sunday near the venue of a rally by Modi in the eastern city of Patna where tens of thousands had gathered to hear him, according to police.

"Late last night, a body was found near the venue, which took the death toll to six. He was then brought to the hospital.... It seems he died of a heart attack," Amarkanth Jha, medical superintendent of Patna Medical College and Hospital, said on Monday.

Indian media, citing unnamed police officials, reported suspicions that the Indian Mujahideen, a home grown Islamist network, were to blame for the blasts.

Modi, a popular but divisive Hindu hardliner, was launching the Bharatiya Janata Party's (BJP) campaign in Bihar state for general elections due next year.

Police said on Monday two people had been arrested and some 13 others detained for questioning, while the national government deployed anti-terror forces to Patna to investigate.

"Through preliminary investigations, it looks like all suspected accused reached Patna on Sunday morning with timer bombs in their bags," local police official Manu Maharaj told AFP on the phone on Monday, adding that a group of six had conducted the Sunday blasts.

One of the arrested, known only as Imtiaz, has "given solid evidence" during interrogation, helping investigations, Maharaj said.

Television footage showed people running from several explosions at the venue, with smoke rising above them.

Police helped carry the injured to hospitals, where mostly men with bloodied bandages were seen lying on beds and hooked up to intravenous drips.

Bihar Chief Minister Nitish Kumar ruled out any political conspiracy and denied any failure of his state's security measures at a press conference on Sunday.