* Rupiah on track for worst session since September 9

* MSCI EM Asia gauge reverses course to trade lower

* Taiwan stocks fall sharply after scaling record high

* KOSPI hits another all-time high

By Rajasik Mukherjee

April 23 (Reuters) - The Indonesian rupiah fell sharply to a record low

of 17,315 against the U.S. dollar on Thursday, a day after the central bank said

it would go all out to defend the "undervalued" currency hammered by capital

outflows.

The rupiah fell 0.7%, heading for its biggest drop since September 9,

pressured by capital outflows on concerns over fiscal sustainability, capital

market transparency issues, and risk-off sentiment caused by the Iran war.

"The rupiah remains under pressure amid concerns around fiscal

sustainability and MSCI-related uncertainty - risks that are unlikely to

dissipate in the near term," ING analysts said on Wednesday after Bank Indonesia

(BI) kept its interest rate unchanged.

"Low oil reserves, limited FX buffers, a wider current account deficit, and

seasonal dividend outflows are likely to keep the IDR trading on the weaker

side, leaving BI with limited room to defend the currency through intervention."

The rupiah has fallen more than 3% this year, and is among the

worst-performing currencies in emerging Asia.

Equities across emerging Asia wavered in early trade. The MSCI EM Asia gauge

erased early gains to trend lower, as Taiwan stocks

reversed sharply, falling 1.7% after rising as much as 2.8% earlier in the day

to a record high.

South Korea's KOSPI index rose 0.8% to another all-time peak, led by

heavyweight chipmakers Samsung Electronics ( SSNLF ) and SK Hynix,

both of which gained more than 3%.

In Southeast Asia, stocks in Singapore fell 1% to their lowest since

April 7, while those in Indonesia slid 0.5% to an eight-session low. The

Philippine peso weakened to 60.473 a dollar, the lowest since April 6.

HIGHLIGHTS:

** Philippine c.bank to hold rates, but decision on a knife edge - Reuters

poll

** Saudi Arabia, Philippines to join JPMorgan emerging market bond index in

2027

** Argentina's Milei proposes elections overhaul, latest effort to shrink

state

** South Korea's Q1 GDP growth roars past market on booming AI-driven chip

demand

Asia stock indexes and currencies at 0253 GMT

COUNTRY FX RIC FX DAILY % FX YTD % INDEX STOCKS STOCKS

DAILY % YTD %

Japan -0.02 -1.79 -1.06 17.11

China -0.02 +2.30 -0.21 3.24

India +0.00 -4.18 0.00 -6.70

Indonesia -0.72 -3.61 -0.64 -13.34

Malaysia -0.28 +2.40 0.50 2.32

Philippines -0.63 -2.76 -0.21 -1.26

S.Korea -0.13 -2.89 0.32 52.78

Singapore -0.08 +0.73 -0.90 6.71

Taiwan +0.05 -0.27 -0.57 30.03

Thailand -0.31 -2.80 - -

(Reporting by Rajasik Mukherjee in Bengaluru; Editing by Subhranshu Sahu)