Is it permissible for an Islamic bank to impose penalty in case receivables are delayed?

delay in serving the liability has to be punishable. It is ultimately the intention which is put to question.

Not really. Islamic Bank must do as per Banking rules and as per signed agreements. Always they are clean and run by Shariah.

It is still controversial issue among scholars. However, it depends on jurisdictions. For instance, in Malaysia, a penalty is imposed on delayed payment but it should be directed to charitable purpose not as revenue for the bank.  I believe that Shariah recognizes the need to recover any damage for the creditors but the problem is just how (mechanism).

Imposing financial penalties on delayed payments is not permissible in Islamic jurisprudence. However, it is practiced that Islamic Financial Institutions (IFIs) may charge penalties on defualt payments but the amount collected of such charges are not included in the income statement of the IFI. Those charges will be used for charitable purposes. 

Charging interest with the intention of giving it for charity is by no means permissible. Interest is unlawful, whether used for personal needs or given in charity.

However, contemporary scholars have mentioned with regards to Islamic Banks that if a client undertakes that in case he defaults in payment at the due date, he will pay a specified amount to a charitable fund maintained by the bank, it will be permissible.