Mr. Hari borrowed a sum of Rs. 60,000/- from a bank on the security of gold on 01.07.2020 under an agreement which contains a clause that the bank shall have a right of particular lien on the gold pledged with it. Mr. Hari, thereafter, took an unsecured loan of Rs. 25,000/-from the same Bank on 01.08.2020 for three months. On 30.09.2020, he repaid entire security loan of Rs.60,000/- and requested the bank to release the gold pledged with it. The Bank decided to continue the lien on the gold until the unsecured loan is fully repaid by Mr. Hari.

Decide whether the decision of the Bank is valid within the provisions of the Indian Contract Act, 1872?