"Modi ji keeps on saying he will transform India's economy, we know now that the beginning of the end has come," Singh said on demonetsation, speaking at the Jan Vedna Sammelan in the national capital.
"Modi ji's propaganda of national income going up in last two years has been proven to be hollow," Singh added.
The former prime minister asserted that things have gone from "bad to worse in the past few months".
"Demonetisation has hurt the country very badly. Things have gone from bad to worse in past few months," the Congress leader said.
The Jan Vedna convention of the Congress party which began at the Talkatora Stadium on Wednesday will focus on the the party's future course of action in its protest against demonetisation.
The party will also pass a resolution to celebrate the 100th birth anniversary of Indira Gandhi in November and release the 'Haal behal, Jan Vedna ke 2.5 saal' booklet.
 "Former prime minister Manmohan Singh")