Feb 8 (Reuters) - Australia's Suncorp Group Ltd posted a near 63% rise in its half-year cash earnings on Wednesday helped by improvement in underlying margins and positive investment returns.

The country's second-biggest insurer by market value posted cash earnings of A$588 million ($408.37 million) for the six months ended December, compared with A$361 million a year ago.

That compares with a UBS estimate of A$674 million. ($1 = 1.4399 Australian dollars) (Reporting by Roushni Nair and Nausheen Thusoo in Bengaluru; Editing by Shailesh Kuber)