In a letter to Rajnath Singh, she said such 'tainted' leaders should not be allowed to be associated with the party and vehemently opposed the entry of B Sreeramalu and Reddy brothers of Bellary into BJP.
She has also opposed the entry of former Union Minister and Congress leader Venod Sharma into Haryana Janhit Party (HJC), which is in alliance with the BJP.
"I am opposed to the BSR alliance or merger with BJP in Karnataka. I have conveyed to Rajnath Singhji in writing that BJP must not permit this," she said.
Her opposition comes after Sreeramalu yesterday announced that his party was merging with the national party two years after he quit the saffron outfit.
This came close on the heels of re-entry of former Karnataka Chief Minister B S Yeddyurappa into BJP after the merger of his outfit Karnataka Janata Paksha. Sushma's open opposition will force the BJP leadership not to take the Reddy brothers back into the party.
The Karnataka unit of BJP is keen to see the merger of BSR Congress in BJP, which is considered to have over 3 per cent votes. The Reddys had quit BJP after their arrest in the mining scam.
Reddys had quit BJP after their arrest in the mining scam.
The Reddy brothers floated their own party called BSR Congress under the leadership of their confidante and former Karnataka minister B Sreeramulu in 2012 to take on the BJP.
The BSR Congress won four seats in the 2013 assembly elections in Karnataka. The Reddy brothers were said to be close to Yeddyurappa.
The three Reddy brothers, Janardhana, Karunakara and Somashekara, were once considered close to Swaraj. Janardhana is in jail in Andhra Pradesh in an illegal mining case and was considered Sreeramulu's mentor, while the other influential brother G Somashekara Reddy is set to follow Sreeramulu back into BJP.
Opposing Venod Sharma's entry into HJC, which is run by Kuldeep Bishnoi the son of former Haryana Chief Minister Bhajan Lal, Swaraj said on twitter, "I am strongly opposed to this. I have conveyed my views to Kuldeep Bishnoi. Venod Sharma set to join HJC."
Post his joining HJC, Sharma is tipped to be the BJP-HJC candidate from Karnal Lok Sabha constituency. HJC is seeking two seats of Hisar, which Bishnoi represents, and Karnal from the BJP under the alliance. Sharma's son Manu is in a Delhi jail in connection with the murder of model Jessica Lall in 1999.