By Stefanno Sulaiman

JAKARTA New certificates being introduced by Bank Indonesia for sale next month are expected to offer "very attractive" yields for foreign investors, an official said on Monday, generating inflows to help keep liquidity supportive for economic growth.

Last week, the central bank announced that it would hold twice weekly auctions of Bank Indonesia Rupiah Securities (SRBI), using BI's holdings of government bonds as underlying assets, from Sept 15.

The instrument was intended to attract capital inflows as well as mop-up excess rupiah liquidity in the domestic financial market, and provide some stability for the rupiah currency at a time when Indonesia's current account and balance of payments have swung into deficit.

Analysts have said the success of the SRBI would depend on what return they offer. On Monday, Edi Susianto, Bank Indonesia's (BI) head of monetary management, provided some key details.

BI would auction 6-, 9- and 12-month certificates every Wednesday and Friday and they would carry similar returns to rates offered for reverse repurchase (RR) of government bonds, Edi told a press conference.

At its last auction on Aug. 18, BI sold 6-, 9-, and 12-month RR contracts with yields of 6.31208%, 6.39517% and 6.41884%, respectively.

"We think these interest rates are very attractive," Edi said. "Of course we think that fundamentally Indonesia is still seen as positive as a place for investment."

He declined to provide guidance on how much SRBI the central bank would sell, but said domestic liquidity would be kept "not too tight", but would be supportive for economic growth, without being excessive.

The SRBI would replace BI's "Operation Twist" in the bond market, where the central bank had been selling its short-term government bonds and vowing to buy long-term bonds whenever yields rise. BI would also stop offering RR of government bonds with similar tenures.

The SRBI could later be expanded to shorter tenures starting from one week and the auction frequency could also be increased, Edi said.

"The impact of SRBI on inflows will ultimately depend on the return being offered, but BI likely sees this as a new instrument that could potentially help manage IDR amidst the market volatility," BofA Global Research economists wrote in a note, highlighting that Indonesia's trade surplus has been shrinking and the current account has returned to a small deficit.

Handy Yunianto, Mandiri Securities' head of fixed income, said the SRBI auctions would provided investors with an alternative as the government reduces its bond sales.

(Reporting by Stefanno Sulaiman; Additional reporting by Fransiska Nangoy; Writing by Gayatri Suroyo; Editing by Martin Petty & Simon Cameron-Moore)