BANGKOK (Reuters) - Thailand's headline inflation rate is expected to have picked up for a third month in June, driven by rising energy and food prices.

The headline consumer price index is seen up 0.50 percent from a year earlier, a Reuters poll of 14 economists showed.

In May, the headline CPI index increased 0.46 percent from a year earlier and it rose 0.07 percent in April, its first annual gain in 15 months.

The deflationary trend, which saw a fall in headline consumer prices, had been mainly sustained by lower global oil prices.

But inflation in Thailand has also been muted by government price controls, subsidies and weak consumption at a time when household debt remains high.

The poll showed annual core inflation rate, which excludes energy and fresh food prices, is expected at 0.80 percent in June, little changed from May's 0.78 percent.

The central bank left the benchmark interest rate <THCBIR=ECI> unchanged at 1.50 percent on June 22. The last change, a 25 basis-point cut, was in April 2015.

(Reporting by Pairat Temphairojana; Editing by Richard Borsuk)