Ansari, an MLA who recently joined the Bahujan Samaj Party (BSP) to contest from Mau Assembly seat in UP, was given custody parole till March 4, enabling him to campaign in the election.
The high court, however, on February 17 had stayed its operation after the poll panel moved a plea seeking cancellation of his parole on the ground that he may influence witnesses in the 2005 murder case of BJP MLA Krishnanand Rai, in which he is facing trial.
Sibal said that the EC should not get involved in the "thicket of politics".
"It (the EC) should remain an independent body. Only in extraordinary situation, the EC can come to court. Participation of candidates in free and fare election is also a basic structure of the Constitution," he submitted.
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The court will now resume arguments on the EC's plea on February 22. Till then Ansari will not be released.
The accused, while seeking the relief, had told the trial court that he has been in judicial custody since December 2005 and was granted parole to contest polls earlier too.
The poll panel has submitted before the high court that besides releasing him on parole, the trial court has also asked the authorities to provide him security with the personnel carrying AK-47 rifles.
The BSP had welcomed the jailed gangster-turned politician and his family after his Qaumi Ekta Dal merged with the party, ahead of the Assembly polls in UP.
The 2005 murder case was transferred from Ghazipur in UP to Delhi by the Supreme Court in 2013 on a plea filed by Alka Rai, wife of Krishnanand Rai.
Ansari, who is at present lodged in Lucknow jail, has over 40 criminal cases against him, including that of murder and kidnapping.