Gal Luft is accused of recruiting and paying a former high-ranking US government official on behalf of principals based in China in 2016, without registering as a foreign agent as required by law.

The classified material was identified by personal attorneys for Biden on Nov 2, days before the midterm elections, Richard Sauber, special counsel to the president, said in a statement.

Concerns have as much to do with the ex-PM's involvement in a forum on democracy, as with the organiser's background.