The number of rigs used by oil and gas explorers in Asia in May rose to the highest in 18 years as demand for energy in the region boosted drilling.

The Asia-Pacific region used 268 rigs on land and sea in May compared with 239 a year earlier, Baker Hughes Inc., an oilfield services company, said on its website. That was the highest in May since 272 were deployed in December 1991.

Crude oil futures in New York gained about 5% in the past year to US$71.40 a barrel as investors bet the world economy will recover from the worst recession since World War II. Economic growth in China and India is rising at more than 7% a year, increasing energy consumption.

Rig use has averaged 260 this year compared with 243 in the Asia-Pacific region last year. That compares with 252 in 2008 when oil prices reached a record US$147.27 a barrel, according to Baker Hughes data. The Asia-Pacific accounted for about 24% of the rigs used in February worldwide, excluding the US and Canada.

The international rig count, excluding US and Canada, stood at 1,090 for the month compared with 993 a year earlier, Baker Hughes said. The count rose by 16 in May from April.

There were 2,750 rigs operating worldwide at the end of May, 74 more than in April, according to Baker Hughes. Rig use was 1,983 a year earlier. The figure includes offshore and onshore drill sites excluding those in Iran and onshore in China.

Baker Hughes has published rig counts since 1944, when Hughes Tool Co. began weekly data on US and Canadian drilling, according to the website. The monthly international rig count started in 1975.