DUBAI, June 3 (Reuters) - Abu Dhabi’s economy expanded an inflation-adjusted 5.2 percent in 2013, its official statistics centre said on Tuesday, a much slower rate than the government had previously estimated but still higher than 4.8 percent in 2012.

The figure from the Statistics Centre Abu Dhabi (SCAD) was much lower than an estimate in February by the emirate’s Department of Economic Development (DED), which said real GDP grew 7.4 percent last year compared with 5.6 percent in 2012.

A DED official told Reuters that the big difference in the two growth figures for last year - equivalent to more than $4 billion - was partly due to a difference in the two institutions’ estimates of oil prices. SCAD officials were not immediately available to comment.

The gap in the estimates underlines the challenges which investors and statisticians face in the Gulf Arab region, where official data is patchy and erratic, making it hard to gauge the real shape of the oil-powered economies.

The contribution of the hydrocarbon sector to Abu Dhabi’s GDP edged down to 51.4 percent in 2013 from 52.4 percent in the previous year, SCAD also said.

Abu Dhabi accounts for about two-thirds of the roughly $400 billion United Arab Emirates economy and almost all of its crude oil exports. The UAE has yet to release its 2013 GDP data.

Analysts polled by Reuters in April forecast the UAE’s economic growth would decelerate marginally to 4.3 percent this year from 4.4 percent in 2013, and further to 4.0 percent in 2015 because of softer oil prices and easing fiscal stimulus.