Where the National Bank is satisfied that owing to unforeseen circumstances the rescheduling of any loans and advances made to artisans, ¹[village and cottage industries, micro enterprises, small enterprises and medium enterprises and those engaged in the field of handicrafts, handlooms and other rural crafts], by any State co-operative bank, regional rural bank or any such financial institution or any financial institution falling under such class of financial institutions as may be approved by the Reserve Bank in this behalf, has become necessary, it may provide to such bank or institution such financial assistance as it may deem fit by way of loans and advances repayable on the expiry of fixed periods not being less than eighteen months and not exceeding seven years against such securities as may be specified in this behalf by the National Bank:
     Provided that no loan or advance shall be made under this section to a State co-operative bank unless such loan or advance is fully guaranteed as to the repayment of the principal and payment of interest, by the State Government but such guarantee may be waived by the National Bank if other security to the satisfaction of the National Bank is furnished, or if, for reasons to be recorded by it in writing, the National Bank is satisfied that the guarantee or other security is not necessary.