Sept 14 (Reuters) - Australia's Citadel Group Ltd, an information technology services provider, said on Monday that an entity owned by the country's biggest private equity firm Pacific Equity Partners (PEP) proposed to buy the software company for A$448.6 million ($326.49 million).

The offer represents a premium of 43.2% to Citadel's closing price on Friday.

($1 = 1.3740 Australian dollars) (Reporting by A K Pranav in Bengaluru; Editing by Jacqueline Wong)