Bank Indonesia (BI) cut the 7-day reverse repurchase rate  by 25 basis points to 5.5.%. Only two of 19 economists in a Reuters poll predicted the cut, the other 17 forecast a hold in the wake of recent global financial volatility.

Last month, BI cut its key rate by 25 basis points (bps), the first loosening since September 2017, which many predicted was the start of an easing cycle that would unwind BI's 175 basis points of tightening in 2018.

That tightening cycle was to support the embattled rupiah  by containing capital outflows linked to U.S. interest rate hikes and the U.S.-China trade war.

Thursday's rate cut would aid economic growth and fits the outlook for inflation to remain low, BI Governor Perry Warjiyo told reporters.

The governor said the cut was "a pre-emptive measure to push forward economic growth momentum from the impact of the global economic slowdown."

He said the central bank would continue with an "accommodative policy mix".

The rupiah strengthened marginally to 14,225 against the dollar on the BI announcement.

Capital Economics said te uncertain outlook for the currency "means that any further loosening is likely to be very gradual".