West Bengal Chief Minister Mamata Banerjee made an unsavoury remark at a rally saying Prime Minister Narendra Modi has "no brains".

"He has been giving false speeches, but what 'mann ki baat' (matters of the heart) when he has no brains," the Trinamool Congress chief said at a rally organised by her party against the land ordinance in Kolkata.

"They are only busy destroying communal harmony. They are destroying the churches... instigating communal violence," Mamata said at the rally.

"We were the first to take up the issue of land acquisition. We have always said we are against forceful land acquisition. We will never bow down before any pressure. We are consistent in our land policy," she said on the controversial ordinance that has seen a united opposition taking on the Modi government.

On the CBI notice to her party seeking details of its accounts, she said, "They want the account details of a poor party like the TMC. And what about them? Do they give any details about their massive expenses in successive elections?"

The acrimony between the ruling Trinamool Congress and the BJP is escalating ahead of the 2016 Assembly elections in the state, which the BJP hopes to make a bipolar contest between the two parties.