"Bajrang Dal (the youth wing of Vishwa Hindu Parishad) and Bharatiya Janata Party are taking money from the ISI. Attention should be paid to this," Singh said on Friday.
Singh also gave a communal dimension to his claim. "Non-Muslims are spying for Pakistan's ISI more than Muslims. This should be understood," he added.
The BJP in Madhya Pradesh has been under fire from the Opposition since last Wednesday, when five persons were arrested in Satna district in a terror-funding racket managed by ISI operatives based in Pakistan. One of those arrested is a Bajrang Dal leader called Balram Singh.
The five arrested were found to have communicated with their handlers using an app which does not keep any record of the messages it sends, police said.
Two years ago, Bharatiya Janata Yuva Morcha (BJYM) leader Dhruv Saxena was arrested in a similar case of espionage and terror-funding in Satna. The accused later got bail. Balram Singh was also a part of this gang.
The remark by Digvijaya Singh, who is known to often put the Congress in a spot with his controversial statements, led to a furore and his name started trending on the social media.
Major Surendra Poonia, a former Indian Special Force member, who recently joined the BJP asked: "Will you share proofs that the BJP took money from ISI?? Communal Propagandist & leaders like you are the biggest threat to India's civilisation! Shame on you."
On Sunday, the Congress leader in a tweet denied accusing the BJP of spying for the ISI in return for money, despite TV channels running recordings of his Friday's statement.
In his subsequent tweet, however, he said the MP Police had arrested Bajrang Dal and BJP IT cell workers spying for Pakistan in return for money. "This is the charge I made and I stand by it. Why don't the TV channels question the BJP on this," he wrote.
( With inputs from IANS )