* OGX committed to over $1 bln in exploration at May auction * Regulator requires financial guarantees by the end of July By Rodrigo Viga Gaier RIO DE JANEIRO, July 10 (Reuters) - OGX Petroleo e Gas SA , the oil and gas unit of Brazilian billionaire Eike Batista's EBX Group, may be allowed to use future output from its offshore Tubarão Martelo field to guarantee new exploration rights bought in May, a source at Brazil's oil regulator, the ANP, told Reuters on Wednesday. A lack of cash at the company, which has struggled with lower than expected oil output, has led it to offer non-cash guarantees to ANP that it will perform required exploration work on Brazilian oil and gas blocks it won in a May auction. Rio de Janeiro-based OGX declined to comment. OGX and partners purchased 13 exploration blocks at the so-called Brazil 11th Round Auction, paying 370 million reais up front for the rights. In the 10 blocks OGX bought alone, it is committed to investing at least 2.6 billion reais ($1.2 billion)on exploration activities and is required to post a bond ensuring its ability to meet that commitment. OGX must provide the guarantee by the end of July or risk losing its rights. Other companies such as state-controlled oil company Petroleo Brasileiro SA, known as Petrobras, regularly use expected future production to provide exploration guarantees, the ANP said. On Monday, Rio de Janeiro-based OGX said it is seeking partners to help honor its commitments. OGX said in May that MPX Energia SA, a sister company in the EBX Group, agreed to take 50 percent of four onshore gas blocks in Brazil's northeastern state of Maranhão. OGX produced 23,000 barrels of oil and natural gas equivalent in June, most of it from an onshore natural gas partnership with MPX. MPX uses the gas to generate electricity. OGX company though has recently scaled back operations, declaring three planned oil fields "non-commerical" and saying its only producing offshore oil field, Tubarão Azul, may cease producing next year, only two years after production started. OGX, whose debt is rated at near-default levels, will likely shrink to a fraction of its former size as part of a wide restructuring of Batista's EBX Group, a source with direct knowledge of Batista's plans told Reuters last week.