Oil giant Shell had "access to everything" being done by the Nigerian government because it had staff in every relevant department, according to the latest US embassy cables revealed by WikiLeaks.
The wires published by the Guardian refer to comments made by Ann Pickard, Shell's then vice-president in Africa, that the government had "forgotten" that the global firm had seconded Shell employees to various ministries.
The notes suggest Shell staff were able to gather inside information about the dealings of the oil-rich state.
In the confidential cable from October 2009, the ambassador wrote that Ms Pickard said Shell had received a copy of a letter from a Nigerian government adviser to the Chinese rejecting an offer for oil exploration blocks.
The cable said: "Pickard said Shell had good sources to show that their data had been sent to both China and Russia.
"She said the GON (Government of Nigeria) had forgotten that Shell had seconded people to all the relevant ministries and that Shell consequently had access to everything that was being done in those ministries."
The ambassador, named by the Guardian as Robin Renee Sanders, also reported Shell was "producing 663,000 barrels per day as of October 13, including the Bonga field".
Among the cables were memos indicating Shell had shared intelligence with the US about "militant unrest" as well as asking for information about rival Russian energy company Gazprom.
A spokeswoman for Shell said the company would not comment on the contents of the leaked cables.