Pan American Energy LLC , a unit of BP Plc (NYSE: BP), is planning to invest $1.4 billion in Argentina's biggest oil field and other areas this year, two sources said on July 14.

The sources spoke on condition of anonymity and said President Mauricio Macri and company executives planned to make an official announcement later on July 14.

Pan American operates in four hydrocarbon basins in Argentina, including the South American country's most productive oil field, Cerro Dragon.

One source said the investment would be in Cerro Dragon and in the provinces of Neuquen and Tierra del Fuego.

Pan American extracts shale gas in Neuquen, and started exploring for unconventional oil there in 2011.

The company has reported a 34% rise in its oil output in Argentina from 2001 to 2015, bringing it to 108,000 barrels per day. Its production of gas rose 67%, to 19 million cubic meters per day, in the same period.