BANGKOK, Aug. 6 (Reuters) – Inflation accelerated in Thailand, Indonesia and South Korea in July, putting pressure on central banks to raise interest rates further despite concerns of slowing Western demand for Asian exports.

Indonesia's inflation rate rose more than expected to a 15-month high in July to stand above the central bank's target range, raising questions over whether policymakers will drop a long-held pledge to leave rates at a record low until 2011.

Thailand's annual inflation rate nudged up to 3.4 percent in July. Although that was below expectations, economists still expect the central bank to raise interest rates again this month by about 25 basis points.

South Korea's consumer price inflation accelerated from June, in line with expectations, but both the government and the central bank have warned that price pressures will start picking up this year as Asia's fourth-largest economy expands.

Official data signals challenges facing Asian policymakers struggling to decide whether to strengthen the pace of growth or to respond more forcefully to faster inflation, especially as prices pick up in big exporting nations such as South Korea and Thailand as trade increases with fast-growing China.

''We could see a rate hike earlier than 2011,'' said Helmi Arman, an economist and bond strategist at Bank Danamon in Jakarta. ''Maybe in November they will start raising the rate.''

Benchmark five-year bond yields rose by 10 basis points to 7.60 percent after the data. Most doubt the central bank will raise rates when it meets on Wednesday though it may signal a more hawkish tone in its monthly policy statement.

Indonesia's central bank has stressed repeatedly it sees no need for a rise this year in its benchmark overnight rate – held at a record low of 6.5 percent since August 2009 – with year-end inflation forecast to fall within its target range.

Indonesia's statistics bureau insisted on Monday prices would not breach the target.

Those expectations are changing. The 6.22 percent rise in Indonesian consumer prices last month from a year earlier clipped the top end of the central bank's forecast range of 4-6 percent and reinforcing growing market expectations of a rise this year.

That compares with a 5.05 percent gain in June and the median forecast in a Reuters survey for a 5.8 percent increase.