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By Nichiket Sunil

April 30 (Reuters) - South Korean and Taiwan stocks were headed on Thursday for their best month in decades, powered by a rally in tech shares, while Indonesia's rupiah fell to a record low after oil prices surged on a report of possible U.S. military intervention in Iran.

The rupiah IDR= shed as much as 0.6% to hit an all-time low of 17,380 per U.S. dollar. The oil-exposed currency has lost 2.3% so far in April in what would be its worst month since October 2024.

Oil prices surged after Axios reported that U.S. President Donald Trump was slated to receive a briefing on new plans for a potential military action in Iran, dashing hopes of lasting peace in the Middle East.

"The Middle East shock has tightened the constraints Indonesia faces. A higher oil bill worsens the fiscal trade-off, and a higher risk premium keeps the IDR more sensitive," said Krystal Tan, Asia economist with ANZ.

Tan also lifts 2026 inflation forecasts for Indonesia to 3.5% from 3.0%, and now expects the Indonesian central bank to increase rates twice, by 25 basis points each, to 5.25% by the end of the year.

South Korean and Taiwan equities were set to post their best monthly gains in decades amid artificial intelligence trade optimism as demand remains strong for chips.

Taiwan stocks .TWII rose 0.2% and were on course for their best month since December 2001. TSMC 2330.TW, the only East Asian-listed firm with a trillion-dollar market value, climbed as much as 1.6%.

Samsung Electronics 005930.KS reported record quarterly profit, driven by a 49-fold jump in chip income, and said it expects a severe supply shortage to deepen next year as clients spend on AI, driving up prices of its memory chips.

South Korean equities .KS11 slipped 0.4% after notching another record high earlier in the session. The benchmark KOSPI was still headed for a nearly 32% jump in April, which would be its best month since January 1998.

Samsung Electronics is up 87% so far this year, while peer SK Hynix 000660.KS has doubled in value.

Jakarta shares .JKSE fell more than 2.4% to hit their lowest since March 16, pulled down by blue-chip stocks, while Philippine stocks .PSI declined 0.6%. For April, the two benchmarks were the only laggards among major Asian indexes.

Asian currencies were subdued. The oil-exposed Thai baht THB=TH weakened to 32.79 per U.S. dollar, while the ringgit MYR= eased 0.5%.

The ringgit remains Asia's best performing currency this year, underpinned by Malaysia's financial and economic stability amid a volatile global market.

The Philippine peso PHP= was marginally up after briefly hitting an all-time low of 61.693 per U.S. dollar.

Meanwhile, China's factory activity expanded for a second straight month in April, as manufacturers cranked up production to ship goods early to buyers worried the Iran war will further inflate costs.


HIGHLIGHTS:
** StanChart profit jumps 17%, books $190 million charge on Iran war
** Japan's factory output in surprise fall as Iran war takes toll on petroleum-based products
** SoftBank plans to list AI and robotics firm Roze in US, FT reports

Asia stock indexes and currencies at 0427 GMT
COUNTRY	FX RIC	FX DAILY %	FX YTD %	INDEX	STOCKS DAILY %	STOCKS YTD %
Japan	JPY=	-0.04	-2.37	.N225	-1.35	14.01
China	CNY=CFXS	+0.04	+2.16	.SSEC	0.09	3.58
India	INR=IN	-0.43	-5.65	.NSEI	-1.07	-8.46
Indonesia	IDR=	-0.54	-4.02	.JKSE	-2.35	-19.81
Malaysia	MYR=	-0.45	+2.22	.KLSE	-0.29	2.10
Philippines	PHP=	+0.06	-4.45	.PSI	-0.64	-3.02
S.Korea	KRW=KFTC	+0.28	-3.02	.KS11	-0.95	57.27
Singapore	SGD=	-0.02	+0.33	.STI	0.75	5.41
Taiwan	TWD=TP	-0.41	-0.79	.TWII	0.48	36.35
Thailand	THB=TH	-0.24	-4.20	.SETI	-0.53	17.80