Library-users are facing hundreds of pounds in fines as a crackdown on the growing number of people still holding on to late books gets under way.
People with overdue library books are facing hefty fines
West Berkshire library service is now warning borrowers who ignore reminder letters about their overdue books they could face fines of more than £100.
Library bosses say the financial cost could be even higher for those still in possession of videos and DVDs.
Invoices for the full replacement value of overdue items are now being issued.
Mike Rodger, the council's executive member for libraries, said: "People who fail to return or renew items in spite of reminders must realise they are using the library unfairly and depriving other people of the opportunity to borrow those books."