But the Supreme Court held otherwise....
The Supreme Court had in ITAT THROUGH PRESIDENT Vs V K AGARWAL AND ANOTHER - had held that the ITAT is a Court and that the Supreme Court had the jurisdiction to punish for contempt of the Income Tax Appellate Tribunal. The Supreme Court held that either the High Court or the Supreme Court can take suo motu action and the party which brings such conduct to the notice of the Court, whether a private person or the subordinate court is only an informant and does not have the status of a litigant in a contempt of court case. Whenever an Act adversely affects the administration of justice or tends to impede its course, or shake public confidence in a judicial institution, the power can be exercised to uphold the dignity of the court of law and protect its proper functioning.
In fact in this particular case, the Supreme Court actually punished the Union Law Secretary for Contempt of the ITAT.
Apparently these facts were not brought to the notice of the High Court in the above case. Browsing TIOL would help.