By Nichiket Sunil

Jan 26 (Reuters) - The Malaysian ringgit and the Singapore dollar jumped to multi-year highs on Monday amid broad U.S. dollar weakness after the yen surged as investors remained on high alert for a possible intervention to support the Japanese currency.

The yen's surge weighed on the U.S. dollar and pulled Asian currencies higher, with the MSCI index of emerging market currencies .MIEM00000CUS rising 0.5% to an all-time high.

Investors were also trimming dollar positions ahead of a Federal Reserve meeting and possible announcement of a new Fed chairman. The Fed is broadly expected to stand pat on rates on Wednesday.

The dollar index =USD, which measures the greenback against six currencies, fell 0.4% to a four-month low.

"We may be on the brink of a sustained breakdown in the broad US dollar index," said Lloyd Chan, a senior currency analyst with MUFG. "On the back of a weaker dollar backdrop, we are seeing broad-based strength across Asian currencies."

The Malaysian ringgit MYR= surged 0.8% to 3.968 per U.S. dollar, its strongest level in more than seven years. The currency, which is among Asia's strongest performers this year, jumped past the psychologically crucial 4 per-dollar level on Friday.

The Malaysian central bank held rates last week and affirmed that last year's growth momentum would seep into the year ahead, raising optimism towards the currency.

The Singapore dollar SGD= strengthened to its strongest level since late-October 2014 and was last at 1.2682 per U.S. dollar.

The Monetary Authority of Singapore $(MAS)$ is expected to leave monetary policy unchanged at a review on Thursday, with the growth outlook supported by strong demand for semiconductor exports and inflation seen under control.

MUFG's Chan said the MAS' policy stance will help support the local dollar. He said the currency is at a "pivotal technical level", where it could gain towards 1.2600-1.2650 per U.S. dollar should the greenback weaken further.

The South Korean won KRW=KFTC, which had lost more than 2.5% in the first three weeks of the month, firmed 1.6%.

The Indonesian rupiah IDR= gained 0.2%, while the Philippine peso PHP= edged up 0.1%.

Regional equities were largely a mixed bag, with Taiwan stocks .TWII edging up to a record, while South Korean shares .KS11 dropped 0.8% after a three-day winning streak.

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(Reporting by Nichiket Sunil in Bengaluru; Editing by Subhranshu Sahu)

((Nichiket.Sunil@thomsonreuters.com))