JAKARTA (AFP) - Indonesia's central bank has moved to shore up its rupiah currency after it hit a four-year low, as foreign investors exit emerging markets due to expectations that huge stimulus schemes in the developed world will soon end.

Developing economies around the world are starting to see their stock markets and currencies tumble on the belief that the United States Federal Reserve will pull the plug on its giant easy money programme.

Bank Indonesia said it would raise the rate it pays lenders for overnight deposits, known as the Fasbi, by 25 basis point to 4.25 per cent effective Wednesday.

Officials hope to encourage lenders to leave their rupiah with the central bank, thereby reducing money supply and, in theory, stopping the rupiah from weakening further. Following the announcement late Tuesday, the rupiah strengthened slightly. By Wednesday afternoon it was at 9,933 against the US dollar, from 10,094 rupiah on Tuesday - its lowest level since 2009.

Analysts said the fall was precipitated by a sell-off in Indonesian bonds and stocks as investors fret about when the Fed will begin to taper its massive programme of bond buying, known as quantitative easing.

The huge central bank spending sprees and low rates in the west aimed at kick-starting growth had led investors to emerging markets in search of better returns, sending markets and currencies soaring. But a pick-up in the US economy has now made US assets and the US dollar look like a better and safer bet.

The Bank of Japan added to investor worries on Tuesday when it decided to hold off any fresh measures to boost its economy after unleashing a giant bond-buying scheme in April.

Jakarta's stock market plunged 3.5 per cent on Tuesday and is down about 13 per cent from its record high seen in May.

The sell-off mirrors similar movements in other developing economies.

India said it intervened in currency markets on Tuesday after the rupee sank to a record low against the US dollar owing to fund outflows.

The Thai baht has tumbled to a nine-month low and the stock market is down more than 10 per cent from May. Manila's stock market is 12 per cent down from its May peak.

There have also been big losses for shares and currencies in other nations, including South Africa and Mexico.

"It feels like the party is ending," Mr Howard Wong, managing director at Doric Capital in Hong Kong, told Dow Jones Newswires.

The rupiah, one of Asia's worst performing currencies in the past year, was already under pressure owing to concern about Indonesia's widening current account deficit, largely blamed on huge fuel subsidies.

Economists said the timing of the rise in the Fasbi rate showed how worried policymakers were, since such decisions are normally taken at central bank policy meetings.

"The timing of this increase came as a surprise, no doubt reflecting central bank concerns that the currency could spin out of control," said Mr Robert Prior-Wandesforde, a Singapore-based economist from Credit Suisse.