General Motors is looking at heading back to court with its lawsuit against Fiat Chrysler, according to a report from the Detroit Free Press that brings new allegations (including an FCA-paid mole) to light.

In a court filing this week, GM claimed that former UAW VP and GM board member Joe Ashton was a paid mole in the GM boardroom during 2015 contract negotiations. The filing also claims that millions of dollars were hidden in offshore bank accounts in places known for their banking secrets rules, used to try and pay bribes to force a merger between GM and FCA.

GM lists former UAW president Dennis Williams as one of the beneficiaries of the accounts, the report says, along with Ashton and FCA labour negotiator Alphons Iacobelli.

The latter two have already been convicted with Ashton admitting conspiring to take bribes and kickbacks connected to the UAW-GM Center for Human Resources and Iacobelli currently in federal prison.

A GM federal lawsuit was dismissed last month, but if the new claims are deemed credible it could raise the stakes of the ongoing suits and investigations.

"New facts about the direct harm FCA caused GM have come to light and they are detailed in our amended racketeering complaint. These new facts warrant amending the court's prior judgment, so we are respectfully asking the court to reinstate the case," GM spokesman Jim Cain told the Free Press in a statement.

An FCA company statement read that "as we have said from the date the original lawsuit was filed, it is meritless. The court agreed and dismissed GM's complaint with prejudice. FCA will continue to defend itself vigorously and pursue all available remedies in response to GM's attempts to resurrect this groundless lawsuit."