Royal Dutch Shell (NYSE: RDSA) on Thursday announced it has deployed an oil spill response vessel in the Gulf of Mexico after an oil sheen appeared near the company's area of operations.

An estimated six barrels of oil has leaked from a source or sources, that Shell officials are still trying to locate.

Shell spokeswoman Kalya Macke said the origin of the leak is unclear but is not related to the company's operations .

According to the company's website, Shell has not lost control of any of its drilling operations in the area.

The oil sheen is spread out over 10 square miles and is located between two of the company's drilling operations roughly 130 miles southeast of New Orleans, reported CNN Money.

Shell is continuing to cooperate with federal regulators in their efforts to determine the cause and nature of the sheen, which is estimated to be six barrels, Shell said on its site. In addition, although we are confident at this time that the sheen did not originate from Shell operations, out of prudent caution we will continue to respond to the sheen.

Along with an ocean-skimming response vessel, the company has also launched observational flights to monitor the size of the sheen, and has also deployed two remote underwater monitoring vehicles to inspect Shell and third-party operations.

The remote vehicles will also work to determine if the oil originated from naturally-occurring oil seeps on the ocean floor.

The spill was reported to the National Response Center late Wednesday, CNN said.

If the spill is found to be linked to Shell's operations, it will be the second such leak in the Gulf since BP's Deepwater Horizon spill in 2010.

In December, a Shell offshore rig off the coast of Alabama spewed thousands of gallons of synthetic, biodegradable drilling fluid into the Gulf. That rig was temporarily abandoned to allow for repairs.

In Thursday trading in New York, Shell's shares fell 19 cents to $67.56.