“I am saddened and disappointed to note that Thiru Manish Sisodia, the elected Deputy Chief Minister of Delhi has been arrested on trumped up allegations and made to undergo all pain and pressure depriving the constitutional guarantee of Personal Liberty. All the canons of criminal justice system have been thrown to the winds and the due process of law has been abused just for personal satisfaction of a ruling party at the Union,” read the letter.

“I therefore appeal to you to take all steps to uphold the residual reputation of the Premier Investigating Agencies and Constitutional offices during the last nine years of BJP rule at the Union, especially the office of the Governor and direct the release of Thiru Manish Sisodia unconditionally, who has been arrested by demeaning the due process of law and fundamental principles of our seven decades old Constitution,” Mr Stalin wrote.

The letter signals a big shift in the stance of the ruling DMK. AAP was not invited for the birthday celebrations of Mr Stalin on March 1, which was attended by Congress chief Mallikarjun Kharge. Party leaders, though, said that invites were sent “only to those who were available to join” that day.

On February 28, the DMK had slammed the arrest in a statement issued by senior leader TR Baalu.