Congress on Monday rubbished demands for resignation of Union Home Minister Shivraj Patil in the wake of Saturday's serial blasts in the capital, alleging the Opposition was playing "cheap politics".

The Congress also sought the cooperation of all state governments and political parties to set up a central agency to investigate terror-related crimes in the country.

"Demands for the Home Minister's resignation at a grave time is nothing but cheap politics by the Opposition party," Congress spokesperson Abhishek Manu Singhvi told reporters.

"How many such times the resignation of L K Advani (Home Minister during NDA regime) was demanded and the same always got rejected by his party," he said retorting that media was speculative and there were no demands from within the UPA for his removal.

Singhvi's remarks came in the backdrop of an indirect attack on the handling of Home Ministry by Railway Minister and RJD chief Lalu Prasad who apparently expressed his displeasure over the situation and demand by Opposition parties for his removal.

Strongly advocating the need for a federal agency for investigating terrorism cases, the Congress spokesperson said, "a central agency is something which is seriously needed."

Noting that the government has a "zero-tolerance" policy towards terrorism, Singhvi said the government needs the "full support" of state governments and parties to get it enacted.