Saudi oil giant Aramco may be more profitable than Apple, according to disputed financial leak

Leaked financial information for the world's largest oil company, Saudi Aramco, reveals one of the most closely held secrets in the energy industry, if the figures are accurate.

Saudi Arabia's national oil company earned $33.8 billion in the first half of 2017, according to financial information obtained by Bloomberg News and disputed by the company.

For comparison, Apple, the world's most valuable publicly traded company, earned $28.9 billion in the same period. Aramco's first-half earnings for 2017 are more than four times the $7.4 billion earned by Exxon Mobil, the largest energy company by market capitalization.

The documents viewed by Bloomberg also lay out other key financial metrics and details of Aramco's royalty structure .

The information potentially offers investors the most comprehensive overview of Aramco's finances yet. The leak comes as Saudi Aramco continues to weigh the right time to launch a public share offering that will almost certainly mark the largest stock market debut ever.

However, Aramco is disputing the report, telling Bloomberg, "This is inaccurate, Saudi Aramco does not comment on speculation regarding its financial performance and fiscal regime."

Aramco did not immediately return CNBC's request to explain which aspects of the financial report and tax information it considers inaccurate.

The information viewed by Bloomberg also says Aramco generated $52.1 billion in cash from its operations, one of the most important metrics in the oil and gas industry. Exxon's cash flow from operations was $15.2 billion during the same period, or $16 billion including asset sales.

A Bloomberg analysis of the data found that Aramco's cost of extracting oil was less than $4 a barrel, significantly lower than its big oil peers.

Several people who are knowledgeable about Aramco's operations told CNBC that figure is likely too low, though the cost is almost certainly in the single digits. Saudi Arabia is often said to break even on new oil production at roughly $5 a barrel.

Aramco paid a $13 billion dividend to its sole shareholder, the Saudi government, Bloomberg reports.

Saudi Arabia cut Aramco's tax rate from 85 percent of its income to 50 percent. The information obtained by Bloomberg lays out a new royalty structure that was also implemented in early 2017.

The royalty is pegged at 20 percent when oil fetches up to $70 a barrel and rises to 50 percent when crude prices break above $100 a barrel. The fee applies to all of Aramco's liquids production, a change from the previous structure, which applied a 20 percent royalty only to exports of crude oil and refined products.