According to the complaint, the securities firms lured five large credit unions into buying more than $3bn in mortgage bonds that were "destined to perform poorly," and that quickly sank the credit unions.

The National Credit Union Administration Board, or NCUA, said that the institutions sold mortgage bonds with loans that didn’t meet underwriting guidelines.

The first two lawsuits seek total damages of $843m, with more lawsuits to follow seeking total damages amounting to billions of dollars.

The two lawsuits filed in the Federal District Court for the District of Kansas seek $278m in damages from JPMorgan Securities and $565m from RBS Securities.

According to media reports, NCUA may file additional lawsuits against as many as eight more banks and securities firms that pooled individual mortgages into securities and sold them to the five credit unions, which failed in 2009 and 2010.

NCUA is a liquidating agent for the failed corporate credit unions, and is an independent federal agency created by the US Congress to regulate, charter and supervise federal credit unions.