(Updates to close)
SYDNEY, Aug 20 (Reuters) - Australian shares posted their lowest close for 2015 on Thursday following a broad-based selloff sparked by worries about slowing Chinese economic growth and uncertainty about when the Federal Reserve will raise U.S. interest rates.
The S&P/ASX 200 index .AXJO fell 1.7 percent, or 91.6 points, to 5,288.6 - the lowest closing level since mid-December.
All the major banks and miners finished in the red. Commonwealth Bank CBA.AX led the big four lenders with a 2.7-percent fall. BHP Billiton (LONDON:BLT) BHP.AX shed 3.1 percent.
New Zealand's benchmark NZX 50 index .NZ50 slipped 0.1 percent, or 7.6 points, to finish at 5,742.5.
(Editing by Shri Navaratnam)