NEW DELHI: The Supreme Court on Tuesday struck down a single directive provision which barred CBI from investigating corruption charges against joint secretary and above rank officers without prior permission of the Centre.The court held as invalid and unconstitutional the provision in the law requiring government's approval to probe senior bureaucrats on corruption charges.All government officials have to be treated equally and have to face the same process of inquiry in graft cases, the SC said, adding, "status of top bureaucrats is of no relevance in the offence under the Prevention of Corruption Act".The apex court said such a classification of bureaucrats for investigation purposes violated Article 14 of the Constitution which mandated that law would treat everyone equally."Prior permission from the Centre to probe corruption charges against joint secretary level officers would fetter the CBI from collecting evidence and also alert the corrupt to destroy evidence," the Supreme Court added."Protection of prior approval for probing graft charges against officers at level of joint secretary and above has propensity of shielding corruption," the Supreme Court said.This is the second time the apex court is striking down the single directive provision in Delhi Special Police Establishment Act.