Shell and Eni have filed internal checks on their purchase of a Nigerian oil field in the US, a news report said.
The documents have been submitted to the US Justice Department and the Securities and Exchange Commission, Reuters reported.
The companies are not being investigated by US authorities, but the acquisition has interest courts in the Netherlands and Italy.
The filings are seen as an attempt to pre-empt a probe in the US.
Shell and Eni paid $1.3billion for offshore licence 245 in Nigeria, but defendants have been accused of involvement in a scheme to defraud the country of a large part of that sum.
Nigeria’s government has said funds were illegally transferred to bank accounts controlled by former oil minister Dan Tete.
Mr Tete led the company which sold the block, Malabu Oil and Gas.
Shell and Eni have denied any wrongdoing.