* News on U.S-China ties, Europe policy easing treated cautiously
* Financial subindex has best week since late May
* Australia's Syrah Resources weighs on mining index (Updates to close)
By Nikhil Subba
Sept 13 (Reuters) - Australian shares eked out a small gain on Friday, helping the benchmark advance for a fourth straight week, but investors stayed cautious in spite of hopes for smoother U.S-China ties and Europe's newly-unveiled monetary stimulus.
The S&P/ASX 200 index .AXJO inched 0.2% or 14.3 points higher to 6,669.20 at the close of trade, helped by the financial sector. The benchmark finished the week up 0.3%.
The United States on Thursday welcomed China's renewed purchases of U.S. farm goods, such as soybeans, while President Donald Trump indicated the possibility of an interim pact with Beijing. European Central Bank (ECB) promised continued stimulus to the ailing euro zone economy through asset purchases. psychology of the market is that they really are waiting for direction in a lot of those international things, particularly the U.S.-China situation", said Doug Symes, senior client adviser at Novus Capital.
All major sectors ended lower on Friday, but the benchmark advanced because of a 0.6% gain for the financial subindex .AXFJ , which reached its highest since Aug. 1.
The subindex rose 2.7% this week, its biggest weekly gain since the one ended May 24.
Symes said the banking sector strength recently reflects that "people are feeling that banks are starting to implement a lot of the things" were requested by a Royal Commission that probed sector behaviour.
Commonwealth Bank of Australia CBA.AX was the best performer among the "Big Four" lenders, climbing about 1% to a near six-week high at close.
Energy stocks .AXEJ reversed course to end the session 0.5% lower, bruised by a decline in oil prices.
Oil and gas major Woodside Petroleum WPL.AX fell 0.4% to its lowest level since Sept. 4, and Oil Search Ltd OSH.AX closed nearly 1% lower.
Graphite miner Syrah Resources SYR.AX dropped about 8%, contributing to the broader mining index's .AXMM 0.1% slip.
Syrah Resources on Friday warned of a production cut in the third quarter and posted a rise in half-yearly losses. Zealand's benchmark S&P/NZX 50 index .NZ50 fell 0.4% or 41.65 points to finish the session at 10,863.41, dragged lower by technology and energy stocks.
Software developer Vista Group International VGL.NZ fell 3%, while fuel retailer Z Energy Ltd ZEL.NZ shed 2.6% at close.