PATNA, INDIA (AFP) - A bomber who blew himself up while trying to evade arrest at a rally by Indian opposition leader Narendra Modi has died of his injuries in hospital, officials said.

Ainul Ansari died late Thursday, four days after suffering serious brain injuries in the blast at the rally in the city of Patna where six other people were killed in a series of explosions.

"He succumbed to his injuries late last night," said Arun Kumar Singh, director of Patna's Indira Gandhi Institute of Medical Sciences.

"A team of five doctors tried their level best to save him but he was unconscious and not responding to any medicines," Dr Singh told AFP.

Dozens of people were also injured in the string of explosions on Sunday, shortly before Mr Modi was due to address a mass gathering of the Hindu nationalist Bharatiya Janata Party (BJP).

Police say that Ansari suffered his injuries while he tried to strap two bombs around his waist.

The bombs went off as he tried to run away from police who had been alerted by a loud explosion when Ansari and another suspect activated an explosive device they prepared in a public toilet at a Patna railway station.

Dr Singh said they had operated twice on Ansari, who had been in a coma since Sunday, but "nothing worked" as he had "splinters, iron pieces in his brain which were difficult to remove".

Ansari was one of four people who had been arrested after the blasts which have been blamed on the Indian Mujahideen, a domestic Islamist network.

The government has since ordered that security be increased at election rallies.

Mr Modi is despised by many Muslims as he was chief minister of Gujarat in 2002 when the state was engulfed by communal riots in which up to 2,000 died.