"They are bringing it through an ordinance. It is just a political gimmick in hurry," he alleged.
He wondered what prevented the government from taking up the Bill "for the last nine years" and holding a debate in Parliament and said the BJP wants a debate on this.
"This Bill has some lacunae. We want to pass it with some modifications. We want a debate on this," he said.
The ordinance on food security gives the country's two-third population the right to get 5 KG of food grains every month at highly subsidised rates of Rs. 1-3 per KG.
The Union cabinet, which had last month deferred a decision on the issue following differences, approved promulgation of an ordinance to implement the Bill.
The programme, when implemented, will be the biggest in the world with an estimated spending of Rs. 125,000 crore annually on supply of about 62 million tonnes of rice, wheat and coarse cereals to 67 per cent of the population.
Singh also defended the Gujarat government in the Ishrat Jahan encounter case, which has been termed as fake by CBI, and sought to enquire the victim's link with terrorist groups.