Nearly a week after a pipeline ruptured on a Royal Dutch Shell operated oil platform in the North Sea, the scale of the spill is becoming clear.

On Monday, the U.K.’s Energy Department described the oil spill as substantial.

“Although small in comparison to the Macondo, Gulf of Mexico, incident, in the context of the U.K. Continental Shelf the spill is substantial,” reads the government statement.

Royal Dutch Shell says that approximately 1,300 barrels of oil leaked into the sea in the incident. The affected well has now been shut off. Shell said in a statement Monday that it estimates that less than five barrels of oil per day is still leaking from the flow line that leads to the platform.

Shell also said it expects the oil slick to disperse naturally and that the oil won’t reach the shore.

The spill occurred just over 100 miles off the coast of Scotland, and is believed to be the worst spill there in over a decade.

Greenpeace U.K., however, accuses Shell of being “less than transparent" in its reporting of the spill. The environmental group complained that even five days after the incident, the oil company had not released enough information to assess the seriousness of the incident.

Monday was the first time since last Wednesday’s incident that the company issued a statement containing substantive details about the amount of oil leaked.

“We are continuing to monitor this situation very closely,” said Scottish Environment Secretary Richard Lochhead in a statement on Monday.

Scottish marine aircraft are surveying the affected area, and fishing vessels were warned of the incident.

Each year, around 900 million barrels of oil are extracted from the U.K. Continental Shelf, with a total of 39 billion barrels over the past four decades. The U.K.’s oil industry employs 32,000 people.

“The U.K. Continental Shelf oil spill record is strong [so it’s] disappointing that this spill has happened,” said spokesperson for the U.K.’s Energy Department in a statement.