RIO DE JANEIRO, April 14 (Xinhua) -- Brazil's state-owned Petrobras, BG Group and Repsol have discovered what could be the world's third-largest oil and gas reserves, Haroldo Lima, director of the National Oil and Gas Agency (ANP), which regulates the sector in the country, said on Monday.

    In a seminar at the Getulio Vargas Foundation in Rio, Lima stressed that the information has not been released "officially" yet.

    He added that, if confirmed, the field, with an estimated volume of 33 billion barrels, in the deep waters of the Santos Basin, in southeastern Brazil, would be the world's biggest oil and gas discovery of the past 30 years.

    According to the ANP director, the field, temporarily named "Sugar Loaf," in reference to Rio's landmark, would be five times larger than Tupi, the giant field discovered in November 2007.

    Tupi is regarded as the largest oil and gas reserve ever found in Brazil, bearing an estimated volume of 5-8 billion barrels of light oil.

    Petrobras' press office has not confirmed the discovery yet, but informed that the Sugar Loaf field is located in block BMS-9 of the Santos Basin, west of the BMS-11, where Tupi was discovered.

    ANP added that the field could not be classified as an "exploitation field" because it has not been declared commercially viable. The first trace of the existence of oil and gas in the field, located in the pre-salt layer, was found in Aug. 2007, but members of the consortium have not released any prospects of its total volume so far.

    The new field is also close to block BMS-24, where Petrobras announced at the beginning of this year to have discovered Brazil's largest natural gas reserve, in the Jupiter field.