whether in criminal defamation case sanction is required for prosecuting public servants or not?

For relevant judgement you can rely upon your lawyer or search for one through internet.

Since an application seeking permission to sue the official is pending you may wait for the orders 

The Supreme Court observed that a minister or public servant (a person covered by Section 199(2)) can file a private complaint alleging defamation and need not follow the special procedure prescribed by Section 199(2) & (4) CrPC."The special procedure is in addition to and not in derogation of the right that a public servant always has as an individual

IN THE SUPREME COURT OF INDIA CRIMINAL APPELLATE JURISDICTION CRIMINAL APPEAL NO. 1791 OF 2022 (Arising out of Special Leave Petition (Crl) No.351 of 2021) MANOJ KUMAR TIWARI                                       … APPELLANT(S) VERSUS MANISH SISODIA & ORS.                                   …RESPONDENT(

Though the above SLP was allowed by supreme court, it was because the contents were not defamatory however it did not mention that the public servants cannot be summoned for the remarks made in their personal capacity. 

the problem projeced herw seems different.

he probably want to file dfamation case agains public servant.

if a public servant has done any crime in pursuance of his duty then saction of the auhroity cimpetent to dismiss himis needed under section 197 of Cr PC