BP spokesman Steve Rinehart was quoted by the Platts news service as saying the company was investigating the incident, believed to have occurred Monday.
"All of the spilled fluids were held in a containment area on the gravel pad that was lined with an impermeable barrier, and we have no evidence that there has been any leakage to the environment," he said.
BP in 2007 pleaded guilty to a Clean Water Act violation stemming from a 5,700-barrel spill from the Prudhoe Bay field the previous year. The U.S. government claims the company violated its probation when about 380 barrels spilled in the same area in 2009.
Federal lawyers, in a late 2011 filing, said the 2009 spill "vividly demonstrates" that BP wasn't serious about safety in its Alaska operations. That spill, the government said, was "predictable and preventable."
The British energy company said it deployed vacuum trucks to the area to clean the site of the Monday incident.