Australia shares ease to 2-1/2-week lows, investors skittish on global worries

* ASX 200 slips 0.3 percent to 2-1/2-week lows

* Australia index set for fourth session of losses

* 71 shares higher, 115 shares lower, 14 shares unchanged (Adds analysis, quotes, stocks on the move)

By Thuy Ong and Gyles Beckford

SYDNEY/WELLINGTON, Aug 6 (Reuters) - Australian shares eased 0.3 percent on Wednesday, falling to 2-1/2-week lows with blue chip stocks pulling the market lower as Wall Street slumped and investors were unnerved by geopolitical tensions.

Among top stocks on the ASX 200, Westpac Banking Corp shed 0.5 percent, while National Australia Bank lost 0.7 percent. Food grocer Woolworths Ltd declined 0.7 percent, while blood products maker CSL Ltd (Other OTC: CMXHF - news) dropped 1.1 percent.

Australia's top telecommunications provider Telstra Corporation Ltd helped buoy the market, adding 0.6 percent to buck the trend.

The S&P/ASX 200 index slid 18.7 points to 5,499.9 by 0222 GMT, set for its fourth consecutive session of losses.

The benchmark hit a six-year high of 5,644.2 on July 31, but has been routed in recent sessions in tandem with Wall Street as investors fret that the U.S. Federal Reserve may raise interest rates sooner than expected.

"We're off to a bit of a tough start this month anyway, you have to remember we were up 4.5 percent last month, so July was the best month for the Aussie market in about a year," said Steven Daghlian, market analyst at Commonwealth Securities in Sydney.

"There's no shortage of geopolitical conerns at the moment, Russia, Ukraine, Middle East, I think that's one thing that's keeping investors on edge too."

For August, the ASX 200 has lost 2.3 percent so far.

U.S. stocks ended down on Tuesday, nose-diving in the afternoon as concerns mounted over escalating tensions in Ukraine.

Polish foreign minister Radoslaw Sikorski said Russia has gathered military forces at the border with Ukraine to either put pressure on the neighbouring country or to enter it.

Elsewhere, the transportation services sector helped cap losses with Transurban Group (Other OTC: TRAUF - news) adding 1.5 percent after it posted a rise of 12.9 percent in toll and other road revenue earnings in the previous session. Sydney Airport Ltd edged 0.2 percent higher, while Asciano Ltd rose 0.7 percent.

Orica Ltd plumbed 2.3 percent to 3-week lows of A$20.87 after the company said it intends to separate its chemicals division either through a demerger or sale, and has received enquiries from third parties expressing preliminary interest.

Adelaide Brighton Ltd gained 1.3 percent after saying it has acquired two integrated aggregates and premixed concrete businesses located in South Australia and Queensland.

Vision Eye Institute Ltd tumbled 8.3 percent to near 3-week lows of A$0.66 after saying it would continue to defend allegations brought against it regarding debts owed.

New Zealand stocks gave back the gains of the previous session with the benchmark NZX 50 index down 0.2 percent to 5,090.80, having dipped to a near-four month low before it trimmed its losses.

Price falls outnumbered the rises two-to-one, with software company Xero, a top-10 stock, falling 3.6 percent to NZ$24.09, a two-week low.

Power generator and retailer Contact Energy (NZSE: CEN.NZ - news) was down 0.9 percent to NZ$5.50.

Partly offsetting the falls were medical equipment maker Fisher and Paykel Ltd, rising 1.3 percent to a near two-month high of NZ$4.81, and Fonterra Shareholders' Fund up 1.3 percent at NZ$6.18.

The latest auction by Fonterra showed a further 8.4 percent fall in prices, but the fund is based on the dividend stream from Fonterra's consumer operations which benefit from lower raw material costs.

(Editing by Jacqueline Wong)