"The BJP government has messed up the economy. The two wings of the government there is working against each other, the atmosphere is deteriorating day in and day out that is obvious from the fact that our borders are insecure, be it cross-border terrorism or internal terrorism".
He stressed that the government should recognize the Jammu and Kashmir's special problems and "we must deal with those problems with all seriousness".
Singh again came down hard on the government over its demonetisation decision and "hurried" implementation of the goods and services tax (GST).
Detailing the Modi government's failure at the economic front, Manmohan Singh said that GST and demonetisation have destroyed jobs.
Singh also dismissed Prime Minister Narendra Modi's comment about farmers' incomes being doubled.
The Congress, at its 84th plenary session that began on Saturday, decided that it would forge workable alliances with like-minded parties as part of efforts to get battle-ready for 2019 general election, with its chief Rahul Gandhi asserting that the country was "fatigued" and only his party could show the way forward.
Singh said the UPA government, which he led from 2004 to 2014, could achieve a lot because of Sonia Gandhi's guidance.
The party also attacked Modi for pursuing a "personalised foreign policy", saying it was "confused and bereft of focus and direction".
He said the defence expenditure of India is no more than 1.6% of the GDP.
Earlier today, Congress leader Anand Sharma said that the PM is carried away by his own propaganda.
The official Indian speeches omitted all mention of Jawaharlal Nehru's and India's contributions to the Non-Aligned Movement, it said.