Every contract entered into by any jute company in relation to any of the undertakings owned by it, which has vested in the Central Government under section 3, for any service, sale or supply and in force immediately before the appointed day, shall, on and from the expiry of a period of one hundred and eighty days from the appointed day, cease to have effect unless such contract is, before the expiry of that period, ratified in writing by the Central Government or the Jute Manufactures Corporation, and in ratifying such contract, the Central Government or the Jute Manufactures Corporation may make such alterations or modifications therein as it may think fit:
     Provided that the Central Government or the Jute Manufactures Corporation shall not omit to ratify a contract and shall not make any alteration or modification in a contract--
         (a) unless it is satisfied that such contract is unduly onerous or has been entered into in bad faith or is detrimental to the interests of the Central Government or the Jute Manufactures Corporation; and
         (b) except after giving the parties to the contract a reasonable opportunity of being heard and except after recording in writing its reasons for refusal to ratify the contract or for making any alteration or modification therein.