* Petrobras share of output slips to 89 pct from 94 pct
* Norway's Statoil regains No. 2 spot, Sinochem No. 3
* Production by EBX Group rises 20 pct
By Jeb Blount
RIO DE JANEIRO, July 3 (Reuters) - Brazil's oil and natural gas output fell in May for a 14th straight month compared with a year earlier as platform repairs at state-run oil company Petroleo Brasileiro SA, or Petrobras, cut production, oil regulator ANP said on Wednesday.
Forty-seven companies combined to produce an average of 2.46 million barrels of oil and natural gas equivalent a day (boepd) in the month, compared with 2.48 million barrels a day in May 2012, the ANP said in a statement.
Output rose 3 percent from April, when Brazil produced an average 2.39 million boepd.
Natural gas output rose from a year earlier by 9.5 percent to an average of 74.9 million cubic meters a day. This helped maintain total production as crude oil output remained below 2 million barrels a day (bpd) for a third month.
Despite the discovery of giant new offshore oil reserves and the billions of dollars of investment being made to develop them, Brazilian output has stagnated for more than a year.
Production has been hurt as Petrobras performs maintenance on offshore oil platforms, output from oil fields declines and new field development is delayed.
The last time Brazilian output rose compared to a year earlier was in March 2012.
Petrobras, while still Brazil's dominant producer, saw its share of Brazilian oil output slip to 89 percent of the national total, one of its lowest levels ever, from 94 percent in March.
Norway's Statoil ASA regained its spot as Brazil's No. 2 producer with 52,276 boepd after completing its own platform repairs.
China's Sinochem, which owns minority, non-operating stakes in fields operated by Statoil and OGX Petroleo e Gas SA moved into the No. 3 spot with 35,850 boepd.
OGX and MPX Energia SA, companies controlled by Brazilian billionaire Eike Batista's embattled EBX Group, saw their combined output rise 20 percent from April to 23,863 boepd.
OGX's offshore output more than tripled to 6,751 boepd, nearly all of it offshore crude, and OGX Maranhão, a joint venture with MPX, saw its output fall 5.5 pct to 17,112 boepd, all of it onshore natural gas.