Accusing West Bengal's ruling Trinamool Congress of encouraging infiltration, the BJP on Monday said the state has become a safe haven for terrorists under the Mamata Banerjee government.

Referring to last year's blast in Khagragarh in Burdwan district in which a Bangladeshi terror outfit was involved, as well as Sunday's arrests of three suspected agents of Pakistan's ISI, BJP national secretary Siddharth Nath Singh accused the Trinamool of having terror links.

"In the last four years, terror activities in Bengal have been growing under the Trinamool. The Khagragarh blast occurred in the house of a Trinamool leader while of the three ISI agents arrested on Sunday, one is a student leader and another a union leader of the Trinamool," said Singh while addressing the BJP's "Utthan Divas" in Kolkata.

"Mamata Banerjee knows no one will vote for her inside the country. So she is bringing in infiltrators for the sake of her vote bank. Under Mamata, Bengal has become a safe haven for terrorists," said Singh, the party's co-in-charge for Bengal.

Attacking the Trinamool over the Saradha scam, Singh, who had given the call of "Bhag Mamata Bhag" (Run Mamata Run), called upon the people to turn that call true in the 2016 Assembly polls.

"Finally, Mamata has admitted that her party leaders are involved in the Saradha scam," said Singh, referring to Banerjee's Monday address in Howrah where she said there can be individual thieves but that doesn't make the party a thief.

"I don't know if her confession is owing to the fact that the CBI is tightening the noose around the Trinamool and also looking at the role played by Madan Mitra's son," said the BJP leader.

Former state transport minister Mitra is one of the accused in the multi-crore scam and is currently in jail.

"Last year, I had given the call 'Bhag Mamata Bhag', and now it is up to you to make that true. It's now time for the people to make Bengal terror free by overthrowing the Trinamool," said Singh.

Speaking in the same vein, BJP national secretary Suresh Pujari also said there was a reign of terror in Bengal under Mamata Banerjee.

"Today, we are celebrating Utthan Divas, but next year on this day, we will be celebrating Vijay Divas, as by then the people of Bengal would have overthrown this reign of terror," said Pujari.