Banca Popolare Italiana, which was caught up in a six-month takeover wrangle for rival Banca Antonveneta, could face costs of over €20m ($23.4m) after Milan prosecutors impounded its Antonveneta stake four months ago.

A source close to the bank said reports in Italian newspaper Il Sole 24 Ore that the seizure was costing €150,000 a day were "plausible'" although he did not know the exact costs related to the shares.