After a year of delays, U.S. prosecutors offered their opening arguments Tuesday in Anchorage at a probation hearing demanding that BP Plc.'s probation be revoked.

The hearing started at 1 p.m. eastern time (9 a.m. in Anchorage) and will last for three more days. U.S. attorneys will have one more day to present their arguments before BP takes the stage on Thursday. A ruling, so far, is not scheduled.

The Anchorage District Court is hearing the case, which originated four years ago.

BP was placed on probation for three years after pleading guilty in 2007 to a 2006 incident which leaked 200,000 gallons of oil in Alaska's Prudhoe Bay.

Two years later in 2009, a pipeline ruptured which spilled an additional 13,500 gallons of oil. The British oil company claims it could not have expected the pipeline to rupture and that until the incident, the pipeline had operated flawlessly, according to court documents.

Stipulations of the company's probation, however, prohibited the company from committing a crime.

Steve Rinehart, a BP spokesman at the hearing in Anchorage, said the company does not deny the pipeline's sudden rupture, but considers what happened to be an accident and not a crime, and thus was not a violation of the company's probation.

But U.S. prosecutors Tuesday in Anchorage argued that the 2009 spill did indeed violate the terms of the company's probation, and that BP was negligent in permitting the spill to happen.

The company has been waiting for this probation hearing to take place since Nov. 17 of last year, when Mary Frances Barnes, the company's probation officer, revoked BP's probation 12 days before it was set to expire. Interestingly, the hearing has been delayed until now, at a time when the company faces continued fallout from its Gulf of Mexico oil spill and legal wrangling that could stretch into 2014.

The probation hearing also comes just as the Obama administration announced Tuesday that BP could face more fines following the Gulf Spill.

Calls for an interview with U.S. attorneys were not answered by press time.