Sheldon Adelson, the gambling magnate and billionaire backer of Republican presidential candidates, made a combative appearance in a Las Vegas court on Tuesday in a case rooted in allegations his casino empire was involved in influence-peddling with a Chinese official and had ties to organized crime.

Adelson, who used his $25bn fortune to back Newt Gingrich and then Mitt Romney as Republican candidates for president, at times expressed outrage at what he said were “delusional and fabricated” allegations against him and his company.

The hearing was called to decide a jurisdictional issue – whether the case should be heard in Las Vegas where Adelson’s company is based or Macau where the allegations are focused. But the high stakes involved were demonstrated by the presence of a Las Vegas gaming commission official monitoring the case because it potentially has implications for the licensing of Adelson’s Las Vegas Sands casino empire.

Adelson is being sued for wrongful dismissal and defamation by the former CEO of his highly profitable operations of a Las Vegas Sands subsidiary in the Chinese enclave of Macau. Steven Jacobs says he was fired in 2010 because he objected to what he alleges were excessive payments to a Macau lawyer and legislator, Leonel Alves, on the grounds they may breach US bribery laws and because he opposed doing business with groups tied to Chinese organized crimes groups, the Triads.