BUDAPEST, March 13 (Reuters) - Hungary's central bank fined 35 banks and financial institutions a total 1.2 billion forints ($5.32 million) for unlawful hikes in fees and costs on Thursday and ordered them to reimburse their clients. The central bank, which also performs financial supervisory functions, said the cost rises over a period from Jan. 1, 2012 to Dec. 31, 2013 breached the law in a number of aspects, such as a failure by banks to inform clients properly. The regulator imposed the biggest fines on Hungary's FHB Bank FHBK.BU , Budapest Bank GE.N , Austria's Erste Bank ERST.VI and Raiffeisen RBIV.VI and MKB Bank BLGGM.UL , which received fines worth nearly 100 million forints each. ($1 = 225.56 Hungarian Forints) (Reporting by Gergely Szakacs; Editing by Erica Billingham) ((gergely.szakacs@thomsonreuters.com)(+36 1 327 4748)(Reuters Messaging: gergely.szakacs.thomsonreuters.com@reuters.net)) Keywords: HUNGARY BANKS/FINE