By Subrata Nag Choudhury and Shounak Dasgupta
KOLKATA/NEW DELHI (Reuters) - A bomb killed two people in West Bengal on Monday, taking the death toll in post-election violence to 15, police said, as workers of India's ruling party clashed with a regional rival in the populous eastern state.
West Bengal, which elects the third largest number of lawmakers to the lower house of parliament, was a key battleground in the general election that Prime Minister Narendra Modi resoundingly won last month, and saw sporadic violence during the 39-day-long poll.
Modi's Bharatiya Janata Party (BJP) picked up 18 of 42 seats in the state, nine times its previous tally, despite a tough fight from the regional Trinamool Congress party, led by the firebrand Mamata Banerjee.
At an event in Kolkata on Tuesday, Banerjee said that two Trinamool supporters were killed after bombs were hurled by unidentified persons on Monday night.
"There is a concerted effort to incite violence in Bengal by the BJP," she said. "They will not succeed."
Since May 23, when election results were announced, at least 15 people have been killed from both parties, a senior police officer said, requesting anonymity since he is not authorised to speak to the media.
On Sunday, India's federal home ministry, which is led by Modi's close aide, Amit Shah, issued an advisory to the West Bengal government, expressing "deep concern" over the violence.
The BJP, which had so far been a bit player in West Bengal's politics, said its workers had been continuously targeted by Banerjee's party.
"Trinamool is losing, they have lost the people's favour and they are trying to retain power through violence," BJP State President Dilip Ghosh told Reuters.
The BJP plans to hold a protest march in Kolkata on Wednesday.
Having consolidated its hold across much of northern and western India, the BJP is trying to make inroads in eastern states like West Bengal.
(Reporting by Subrata Nag Choudhury in Kolkata and Shounak Dasgupta in New Delhi; Editing by Nick Macfie)