"We have not yet taken any decision; ...law department is examining, they are studying the judgement, we will take a decision after getting inputs from them," Siddaramaiah said.
"We will consider the opinion of Special Public Prosecutor B V Acharya and also the opinion from Law department and the Advocate General and then take a decision," he told reporters in New Delhi.
Responding to a question, he said he had not contacted the party (Congress) high command on the issue.
The Karnataka high court gave a clean chit to the All India Anna Dravida Munnetra Kazhagam chief and three others, clearing them of "all charges" in the 19-year-old case on May 11, paving the way for return of Jayalalithaa, who was chosen as legislature party leader by her party in Chennai on Friday, as CM.
Meanwhile, Advocate General Ravivarma Kumar has said that he has advised the state government to file an appeal.
"The judgement has flaws, so appeal has to be filed. I have advised the Karnataka government that as Karnataka is the sole prosecutor, it has to file an appeal," Kumar told a television channel.
He said "as per law there is a 90-day time from the day the high court gave its verdict, to file an appeal."
Karnataka Law and Parliamentary Affairs Minister T B Jayachandra had earlier this week said that the government would take "some more days" to decide on filing an appeal in the Supreme Court.
B V Acharya has also made public his advice that he has asked Karnataka government to file an appeal as it was a "fit case" to do so.
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