New Delhi | Ahead of phase two of polling in West Bengal, the Election Commission has asked the National Investigation Agency to ensure bombs are not used by miscreants to disrupt voting and target workers of political parties, poll authority officials said on Tuesday.

The directive comes after recovery of crude bombs in the poll-bound state and reports of a minor blast.

While the phase one of polls in the state took place on April 23, the second phase will be held Wednesday.

EC officials said the poll body is taking stringent measures to prevent any poll-day or post-poll violence in West Bengal.

On April 26, police recovered crude bombs from the house of a person, allegedly a TMC worker, at Bhangar in South 24 Parganas district.

Later, on a directive by the Union Home Ministry, the National Investigation Agency (NIA) registered a case to probe the recovery of 79 crude bombs in the state.

In pursuance to the home ministry's order, the anti-terror agency on Sunday registered a case, which was originally filed at Uttar Kashi police station, Bhangar division, Kolkata on Saturday, and took up the investigation, an NIA spokesperson had earlier said.

"The case pertains to recovery of 79 crude bombs and other incriminating materials by Kolkata police, which were being stored at a spot, thereby endangering human life and property," the spokesperson had said.

Amid law and order concerns in West Bengal, the EC had earlier this month decided to continue deployment of 500 companies of central forces in the state even after counting of votes on May 4.

"During the last assembly elections, there was post-poll violence. The decision is also based on past incidents," an official explained.