The Philippine central bank will follow its surprise July rate hike with a half-point point rise on Thursday and another quarter-point increase in September to catch up with its peers in containing soaring inflation, a Reuters poll forecast.

Driven by higher transport and food prices, inflation in the Southeast Asian nation accelerated to 6.4% in July, its fastest pace in nearly four years, pushing the central bank to tighten monetary policy at a faster pace.

The Bangko Sentral ng Pilipinas (BSP) followed two modest quarter-point rate rises so far in this cycle with a hefty unscheduled 75 basis point rise on July 14, its most aggressive since the central bank shifted to an inflation-targetting approach in 2002.

The Aug. 8-15 Reuters poll showed nearly 70% of economists, 11 of 16, forecast the BSP would hike its key overnight reverse repurchase facility rate by another 50 basis points to 3.75% at its Aug. 18 meeting. Four expected a 25 basis point hike, while one said no change.

A strong 60% majority of economists, 10 of 16, forecast another 25 basis points hike at the September meeting, taking rates to 4.00%, where they were before the pandemic.

Seven economists forecast rates to reach 4.25% or higher by end-2022. Six expected rates to reach 4.00%, while the remaining three said 3.75% or lower.

"Governor (Felipe) Medalla has stated that a 25 or a 50 bp hike is likely in August, and we think higher-than-expected inflation suggests that the BSP will take the faster approach," noted Shreya Sodhani, research analyst at Barclays.

"This would also be consistent with the BSP's commitment to do more to get inflation in line with its target range, as it showed with the large frontloaded hike in July."

Price pressures are widely expected to remain elevated in the coming months and a weaker peso, which has already fallen 9% this year, has further worsened the outlook through imported inflation.

Inflation was not forecast to fall within the target range of 2%-4% until mid-2023, according to a separate Reuters poll taken in July, largely in line with the central bank's projection.

Last month, the central bank chief ruled out another surprise move on rates, signalling the next move would be smaller than the 75 basis points delivered in July.

Although annual growth slowed from 8.2% in the first quarter to 7.4% in the last one, it was still the second-fastest so far in Asia, giving the central bank room for further tightening.

BSP has raised rates by 125 basis points since May.