Addressing a public meeting at Chanditala in West Bengal's Hooghly district, Kalyan said, " His (Siddharth Nath Singh's) behaviour seems that he is a blot in the family of former Prime Minister Lal Bahadur Shastri,"
Kalyan contended that it was his reaction against Singh's earlier remark (Bhaag Mamata Bhaag) insulting Trinamool Congress chief Mamata Banerjee.
Siddharth Nath Singh is the grandson of Lal Bahadur Shastri.
"If I have hurt anyone, I express my regret," he said after Speaker Sumitra Mahajan told him that he should express regret though she cannot force him to do so."
The TMC MP even said, "It was not my intention to insult the Prime Minister or show disrespect to Lal Bahadur Shastriji. I respect both of them.