"I think the way this trend has increased, I feel it increased after the announcement declaring (Modi) as the campaign committee chief, it is going to increase further in future," he added while addressing a national committee meeting of BJP's Information Technology (IT) cell in New Delhi.
Singh asked the party's "e-workers" to tell the people through the social media of these attempts to "malign" Modi.
The BJP chief said the government perceives that it cannot win the next elections on the basis of achievements.
To divert the attention of the people from its "failures", the government is trying another method, it is trying to make it an issue of communalism versus secularism, he added.
"We need to tell the people through social media that the Congress is the biggest communal party in the country," Singh told his party's IT cell.
He said that despite having ruled the country for a long time, the Congress government had "failed" to create social harmony.
Singh also told the members of IT cell of his party that there is need to highlight the "failures" of Congress-led UPA government among the people. He said people should be told that the value of the money they are earning is coming down.