Newfoundland and Labrador Premier Danny Williams says ExxonMobil has reneged on its promise to let an independent auditor look at the company's books on the Hibernia development.

Williams said ExxonMobil complained last year that it was not getting as much from the offshore oil project as had been expected when the development was getting underway in the 1990s.

At the time, both sides were trying to work out a deal to develop the Hebron oil field. Williams said the company is lowballing Hibernia's benefits in part to give it an edge during the Hebron talks.

Williams said the government agreed last summer to review ExxonMobil's concerns if an independent auditor could assess the company's numbers.

He said the consultant went through the government's figures, but when it came time for ExxonMobil to open its books, the company denied auditors any access.

Williams is calling on Hibernia to open its books and back up its claims that Hibernia is not paying off as much as expected.

"I think it's incumbent on government to let the people of the province know, let the business community know, let the oil industry know in this province that, you know, what we're asking for here is not unfair," said Williams.

ExxonMobil declined to comment Wednesday on the premier's allegations.

Williams also released numbers Wednesday that he believes show the Hibernia project has delivered unexpected billions to companies like ExxonMobil.

He said that, despite ExxonMobil's lack of cooperation, the province's hired auditors still compiled and analyzed all information readily available on the project.

Williams said they found the total royalties to date on the Hibernia project have been $587 million since first oil in 1997 and that gross revenues have increased to $19.9 billion from $14.6 billion.

Williams said he has written the federal government about ExxonMobil's broken promise because Ottawa has a minority share in the Hibernia consortium.