(c) 2013, Bloomberg News.

(c) 2013, Bloomberg News.

JAKARTA, Indonesia Bank Indonesia raised its benchmark interest rate by half a percentage point Thursday in an unscheduled move, joining the biggest emerging markets in implementing measures to shore up slumping currencies. The rupiah rose.

The central bank increased the reference rate to 7 percent from 6.5 percent, it said, after a meeting in Jakarta that came before the next scheduled policy review. It also raised the deposit facility rate by half a point to 5.25 percent, and extended a bilateral swap deal with the Bank of Japan valued at $12 billion that will allow the two to borrow from each other's foreign-exchange reserves.

Indonesia joins Brazil, Turkey and India in taking steps to support their currencies this month as the prospect of reduced U.S. monetary stimulus prompts investors to sell emerging-market assets. A record current-account deficit last quarter for the Southeast Asian nation, and worse-than-estimated economic growth and inflation data have led to a stock-market slump and helped push the rupiah to its weakest level since April 2009 yesterday.

"What they can do now is to limit the collateral damage from the potential U.S. policy shift," said Wellian Wiranto, a Singapore-based investment strategist at the wealth management unit of Barclays. "The Fed's previously abundant fountain of liquidity is turning into a black hole pulling everything in. BI can only try to anchor things as much as they can."

The rupiah advanced for the first time this week after the rate increase, rising 0.1 percent to 10,935 per dollar as of 4:53 p.m. in Jakarta, after reaching a four-year low of 10,955 yesterday, prices from local banks show.

Brazil's central bank raised its key interest rate by a half-percentage point for a third straight meeting Wednesday, and signaled the world's most-aggressive tightening cycle will continue at the current pace to keep a weaker real from fueling inflation. The combined 175 basis-point surge in borrowing costs over the past four central bank gatherings is the fastest expansion among 49 major economies tracked by Bloomberg.

The Reserve Bank of India said Wednesday it will supply dollars to top oil importers after the rupee plummeted to a record low of 68.8450 per dollar. Turkish central bank Governor Erdem Basci said this week he will use "surprise" tools to fight a deepening slump in the lira and will defend the currency "like lions."

"What the market is looking for is more comprehensive and coordinated policy response from both central banks and also the government, particularly for countries with deficits, who need to show that they have a strong plan for reducing the current account deficit," said Khoon Goh, a senior currency strategist at Australia & New Zealand Banking Group Ltd. in Singapore.

Local stocks and government bonds extended gains, with the Jakarta Composite Index of shares closing 1.9 percent higher. The yield on sovereign debt due May 2023 fell 13 basis points, or 0.13 percentage point, to 8.73 percent, after earlier touching the highest level since February 2011, according to prices from the Inter Dealer Market Association.

Indonesia raised the key rate by a combined 75 basis points in June and July before keeping it unchanged at its meeting on Aug. 15 as slowing growth deterred a third consecutive increase. The rupiah's more-than-5 percent slump in the past two weeks may have pressured the central bank to increase borrowing costs again before a scheduled policy review on Sept. 12.

"The central bank is finally responding to the market pressure," Jemmy Paul, a Jakarta-based equity fund manager at Sucorinvest Asset Management, said in an email. If the rupiah remains weak, there will be more tightening measures, he said.

Indonesia's bilateral swap deal with the Bank of Japan, in place since 2003, was due to expire Aug. 31, said Peter Jacobs, director of communications at Bank Indonesia. It has been renewed every two years, he said.

"The outlook for monetary policy depends largely on what happens to the currency," Gareth Leather, a London-based Asia economist at Capital Economics Ltd., said in a note after the Indonesian rate decision. "We believe that the current bout of currency volatility will prove short-lived and that a prolonged reversal of capital flows is unlikely. In such circumstances, further aggressive rate hikes in Indonesia are unlikely."

_ With assistance from Berni Moestafa, Neil Chatterjee, Yudith Ho and Andrew Janes in Jakarta.