Brazilian authorities identified a small oil leak off the shores of Rio de Janeiro on Saturday, the latest in a series of spills that has raised safety concerns over the development of some of the world's largest petroleum reserves.

The latest oil leak comes days after a Brazilian prosecutor said he is widening a probe into offshore oil operations in the wake of a 3,000-barrel spill in an offshore field run by Chevron in November.

The new leak, which stretches for 1.2 miles (2 km), is estimated at 1,600 litters of oil (14 barrels) and remains far away from the coast, Rio de Janeiro's state Environmental Institute said in a statement. Officials were due to test the oil to try to determine its origin, but the leak is believed to have come from a ship in a sea route heavily transited by oil tankers.

The leak was in the Campos Basin, which extracts about 80 percent of the country's output of more than 2.6 million barrels of oil per day. The area is believed to hold to some of the world's top oil reserves and that has attracted major producers such as Petrobras, Anglo Dutch Shell UK-based BP and Spain's Repsol YPF.

A small leak in Chevron's Frade field two weeks ago led the company to shut down production at the field, which has produced as much as 80,000 barrels per day.

That leak and the November spill prompted criminal charges against the U.S. No 2 oil company, its drilling contractor Transocean and 17 of their employees.

Chevron and Transocean dispute the charges, which have cast a shadow over the development of Brazil's booming oil industry.

(Reporting By Alonso Soto; Editing by Will Dunham)