The cases in US and Canadian courts centre on corruption allegations levelled by state-owned Saudi companies against Saad Aljabri, a former spymaster who long worked closely with American officials on covert counterterrorism operations.

That marks the latest twist in a long-running feud between Crown Prince Mohammed bin Salman (MBS) and Aljabri.

Aljabri's patron, Prince Mohammed bin Nayef (MBN), is currently in Saudi detention after being deposed as heir to the throne in a 2017 palace coup.

The legal drama sheds light on Shakespearean rivalries in the top echelons of the Saudi royal family, but Washington fears that a bitter courtroom showdown risks exposing sensitive information related to its covert operations.

A rare US Justice Department filing in a Massachusetts court in April noted Aljabri's intention to "describe information concerning alleged national security activities".

"The (US) government is considering whether and how to participate in this action, including if necessary and applicable, through an assertion of appropriate governmental privileges," the filing said, without elaborating.

In a second filing a month later, the Justice Department asked the court for more time as national security matters require "'delicate' and 'complex' judgements by senior officials".