Any person including any department of the Government aggrieved by any decision or order of the National Tax Tribunal may file an appeal to the Supreme Court within sixty days from the date of communication of the decision or order of the National Tax Tribunal to him:

   Provided that the Supreme Court may, if it is satisfied that the appellant was prevented by sufficient cause from filing the appeal within the said period, allow it to be filed within such time as it may deem fit.