A pipeline company has been indicted on criminal charges over a massive California oil spill last year that forced the shutdown of beaches and killed hundreds of animals, authorities said on Tuesday.

Plains All-American Pipeline faces 46 criminal charges while one of its employees was indicted on three criminal charges.

"Crimes against our environment must be met with swift action and accountability," California Attorney Kamala Harris said in announcing the indictment.

"The carelessness of Plains All-American harmed hundreds of species and marine life off Refugio Beach. This conduct is criminal and today's charges serve as a powerful reminder of the consequences that flow from jeopardizing the well-being of our ecosystems and public health."

The Texas company faces up to $2.8 million in fines and additional penalties, officials said.

The pipeline rupture last May resulted in 140,000 gallons of heavy crude oil being released along the Santa Barbara County coast, forcing the shutdown of many of the area's popular beaches and leading to the deaths of hundreds of animals, including sea lions and pelicans.

The company said in a statement that the oil spill was accidental and that the criminal charges are unwarranted.

"We will vigorously defend ourselves against these charges and are confident we will demonstrate that the charges have no merit and represent an inappropriate attempt to criminalize an unfortunate accident," it said in a statement.