Under fire over forming a separate Anti-Corruption Bureau, Karnataka Chief Minister Siddarmaiah has written to his party top brass Sonia Gandhi and Rahul Gandhi defending the move, even as he rejected the Opposition demand for ACB withdrawal in the Assembly on Tuesday.

Siddarmaiah has "assured" Congress President Sonia Gandhi that what has been done in Karnataka is in tune with the pattern prevailing in at least 12 other important states, officials in CM's office said.

"It is the endeavour of our Government to give more attention and focus to fighting corruption in the system. In view of that, ACB has been set up and I am confident that this will deliver better results than what is happening at present," a part of the letter shared with media read.

Siddaramaiah has also written similar letters to Congress Vice President Rahul Gandhi, General Secretary Digvijay Singh, and Leader of the party in Lok Sabha Mallikarjuna Kharge.

In the Assembly, Siddaramaiah maintained that there was no "mala fide" intention to shield the corrupt or to weaken the Lokayukta through the constitution of ACB.

Replying after BJP and JDS called off their dharna in the well of the House demanding withdrawal of ACB, he said he was willing to discuss with the opposition ways to strengthen Lokayukta. Countering the BJP attack, Siddaramaiah said the police wing in the Lokayukta would also continue and a similar system prevailed in 15 states.

"There is no mala fide intention behind our decision. Nor are we trying to shield anyone," he said.

Refusing to step back, he said, "There is no question of withdrawing the ACB."

Leader of the Opposition Jagadish Shettar (BJP) said the ACB should be withdrawn "at any cost" and his party would take the fight to outside the House and announced withdrawal of their protest to facilitate smooth functioning to discuss other "burning" issues like drought situation in the state.

Opposition BJP and JD(S) have accused government of "destabilising" Karnataka Lokayukta by creating ACB, and have demanded its immediate withdrawal.

Meanwhile, BJP state President Prahlad Joshi has also written to Sonia Gandhi requesting her to advise the Karnataka government against creating ACB and instead make Lokayukta stronger.