What to do when the lender cannot be found? The Grand Ayatollah Shobairi’s answer

The Grand Ayatollah Shoabairi  Zanjani answered a question about not being able to find the lender.

Question: I have some debts to pay back and lost hope of finding the lenders, is paying to charity on their behalf is an immediate necessity or not?

The Grand Ayatollah Shoabairi: Yes, it must be paid in the first possible opportunity, with the permission of the fully qualified Mojtahid.